lint_couponcode.c File Reference

Purpose

The couponcode linter ensures that the data conforms to the original North American Coupon Code (NACC) specification, as carried in AI (8110).

Remarks

Refer to the document "North American Coupon Application Guideline Using GS1 DataBar Expanded Symbols" for a description of the GS1 U.S. coupon code data content.

Functional Description

gs1_lint_couponcode()

GS1_SYNTAX_DICTIONARY_API gs1_lint_err_t gs1_lint_couponcode	(	const char *const	data,
		size_t *const	err_pos,
		size_t *const	err_len
	)

Used to ensure that an AI component conforms to the North American Coupon Code (NACC) specification, as carried in AI (8110).

Parameters

[in]	data	Pointer to the null-terminated data to be linted. Must not be NULL.
[out]	err_pos	To facilitate error highlighting, the start position of the bad data is written to this pointer, if not NULL.
[out]	err_len	The length of the bad data is written to this pointer, if not NULL.

Returns

GS1_LINTER_OK if okay.

GS1_LINTER_COUPON_MISSING_GCP_VLI if the data is missing a primary GCP VLI.

GS1_LINTER_COUPON_INVALID_GCP_LENGTH if the data contains a primary GCP with an invalid length.

GS1_LINTER_COUPON_TRUNCATED_GCP if the data contains a primary GCP that is shorter than is indicated by its VLI.

GS1_LINTER_COUPON_MISSING_SAVE_VALUE_VLI if the data is missing a Save Value VLI.

GS1_LINTER_COUPON_INVALID_SAVE_VALUE_LENGTH if the data contains a Save Value VLI with an invalid length.

GS1_LINTER_COUPON_TRUNCATED_SAVE_VALUE if the data comtains a Save Value that is shorter than is indicated by its VLI.

GS1_LINTER_COUPON_MISSING_1ST_PURCHASE_REQUIREMENT_VLI if the data is missing a primary purchace Requirement VLI.

GS1_LINTER_COUPON_INVALID_1ST_PURCHASE_REQUIREMENT_LENGTH if the data contains a primary purchase Requirement VLI with an invalid length.

GS1_LINTER_COUPON_TRUNCATED_1ST_PURCHASE_REQUIREMENT if the data comtains a primary purchase Requirement that is shorter than is indicated by its VLI.

GS1_LINTER_COUPON_MISSING_1ST_PURCHASE_REQUIREMENT_CODE if the data is missing a primary purchase Requirement Code.

GS1_LINTER_COUPON_INVALID_1ST_PURCHASE_REQUIREMENT_CODE if the data contains a primary purchase Requirement Code that is too short.

GS1_LINTER_COUPON_TRUNCATED_1ST_PURCHASE_FAMILY_CODE if the data contains a primary purchase Family Code that is too short.

GS1_LINTER_COUPON_MISSING_ADDITIONAL_PURCHASE_RULES_CODE if the data contains an optional field 1 that is missing an Additional Purchase Rules Code.

GS1_LINTER_COUPON_INVALID_ADDITIONAL_PURCHASE_RULES_CODE if the data contains an optional field 1 whose Additional Purchase Rules Code is invalid.

GS1_LINTER_COUPON_MISSING_2ND_PURCHASE_REQUIREMENT_VLI if the data contains an optional field 1 that is missing a second purchase Requirement VLI.

GS1_LINTER_COUPON_INVALID_2ND_PURCHASE_REQUIREMENT_LENGTH if the data contains an optional field 1 with a second purchase Requirement VLI with an invalid length.

GS1_LINTER_COUPON_TRUNCATED_2ND_PURCHASE_REQUIREMENT if the data contains an optional field 1 whose second purchase Requirement Code is shorter than is indicated by its VLI.

GS1_LINTER_COUPON_MISSING_2ND_PURCHASE_REQUIREMENT_CODE if the data contains an optional field 1 that is missing a second purchase Requirement Code.

GS1_LINTER_COUPON_INVALID_2ND_PURCHASE_REQUIREMENT_CODE if the data contains an optional field 1 whose second purchase Requirement Code is invalid.

GS1_LINTER_COUPON_TRUNCATED_2ND_PURCHASE_FAMILY_CODE if the data contains an optional field 1 whose second purchase Family Code is too short.

GS1_LINTER_COUPON_MISSING_2ND_PURCHASE_GCP_VLI if the data contains an optional field 1 that is missing a second purchase GCP VLI.

GS1_LINTER_COUPON_INVALID_2ND_PURCHASE_GCP_LENGTH if the data contains an optional field 1 with a second purchase GCP VLI with an invalid length.

GS1_LINTER_COUPON_TRUNCATED_2ND_PURCHASE_GCP if the data contains an optional field 1 with a second purchase GCP that is shorter than indicated by its VLI.

GS1_LINTER_COUPON_MISSING_3RD_PURCHASE_REQUIREMENT_VLI if the data contains an optional field 2 that is missing a third purchase Requirement VLI.

GS1_LINTER_COUPON_INVALID_3RD_PURCHASE_REQUIREMENT_LENGTH if the data contains an optional field 2 with a third purchase Requirement VLI with an invalid length.

GS1_LINTER_COUPON_TRUNCATED_3RD_PURCHASE_REQUIREMENT if the data contains an optional field 2 whose third purchase Requirement Code is shorter than is indicated by its VLI.

GS1_LINTER_COUPON_MISSING_3RD_PURCHASE_REQUIREMENT_CODE if the data contains an optional field 2 that is missing a third purchase Requirement Code.

GS1_LINTER_COUPON_INVALID_3RD_PURCHASE_REQUIREMENT_CODE if the data contains an optional field 2 whose third purchase Requirement Code is invalid.

GS1_LINTER_COUPON_TRUNCATED_3RD_PURCHASE_FAMILY_CODE if the data contains an optional field 2 whose third purchase Family Code is too short.

GS1_LINTER_COUPON_MISSING_3RD_PURCHASE_GCP_VLI if the data contains an optional field 2 that is missing a third purchase GCP VLI.

GS1_LINTER_COUPON_INVALID_3RD_PURCHASE_GCP_LENGTH if the data contains an optional field 2 with a third purchase GCP VLI with an invalid length.

GS1_LINTER_COUPON_TRUNCATED_3RD_PURCHASE_GCP if the data contains an optional field 2 with a third purchase GCP that is shorter than indicated by its VLI.

GS1_LINTER_COUPON_TOO_SHORT_FOR_EXPIRATION_DATE if the data contains an optional field 3 whose expiration date is too short.

GS1_LINTER_COUPON_INVALID_EXIPIRATION_DATE if the data contains an optional field 3 whose expiration date is invalid.

GS1_LINTER_COUPON_TOO_SHORT_FOR_START_DATE if the data contains an optional field 4 whose start date is too short.

GS1_LINTER_COUPON_INVALID_START_DATE if the data contains an optional field 4 whose start date is invalid.

GS1_LINTER_COUPON_EXPIRATION_BEFORE_START if the data contains an optional field 3 and an optional field 4 where the expiration date is prior to the start date.

GS1_LINTER_COUPON_MISSING_SERIAL_NUMBER_VLI if the data contains an optional field 5 that is missing the Serial Number VLI.

GS1_LINTER_COUPON_TRUNCATED_SERIAL_NUMBER if the data contains an optional field 5 whose Serial Number is shorter than indicated by its VLI.

GS1_LINTER_COUPON_MISSING_RETAILER_GCP_OR_GLN_VLI f the data contains an optional field 6 that is missing the Retailer GCP/GLN VLI.

GS1_LINTER_COUPON_INVALID_RETAILER_GCP_OR_GLN_LENGTH if the data contains an optional field 6 with a Retailer GCP/GLN VLI with an invalid length.

GS1_LINTER_COUPON_TRUNCATED_RETAILER_GCP_OR_GLN if the data contains an optional field 6 whose Retailer GCP/GLN is shorter than indicated by its VLI.

GS1_LINTER_COUPON_MISSING_SAVE_VALUE_CODE if the data contains an optional field 9 that is missing the Save Value Code.

GS1_LINTER_COUPON_INVALID_SAVE_VALUE_CODE if the data contains an optional field 9 whose Save Value Code is invalid.

GS1_LINTER_COUPON_MISSING_SAVE_VALUE_APPLIES_TO_ITEM if the data contains an optional field 9 that is missing the Save Value Applies to Item value.

GS1_LINTER_COUPON_INVALID_SAVE_VALUE_APPLIES_TO_ITEM if the data contains an optional field 9 whose Save Value Applies to Item value is invalid.

GS1_LINTER_COUPON_MISSING_STORE_COUPON_FLAG if the data contains an optional field 9 that is missing the Store Coupon Flag.

GS1_LINTER_COUPON_MISSING_DONT_MULTIPLY_FLAG if the data contains an optional field 9 that is missing the Don't Multiply Flag.

GS1_LINTER_COUPON_INVALID_DONT_MULTIPLY_FLAG if the data contains an optional field 9 whose Don't Multiply Flag is invalid.

{
 
        gs1_lint_err_t ret;
        size_t pos;
        int vli;
        const char *p, *q;
        char expiry_date[7] = {0};
        int expiry_set = 0;
        char gcp[14] = {0};
 
        assert(data);
 
        /*
         * Data must consist of all digits.
         *
         */
        if ((pos = strspn(data, "0123456789")) != strlen(data))
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_NON_DIGIT_CHARACTER,
                        pos,
                        1
                );
 
        p = data;
        q = data + strlen(data);
 
 
        /*
         * Validate that the GCP follows its VLI and has the corresponding
         * length (plus 6).
         *
         * Valid GCP VLIs are "0" to "6".
         *
         */
        if (p == q)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_MISSING_GCP_VLI,
                        0,
                        (size_t)(q - data)
                );
        if (*p > '6')
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_INVALID_GCP_LENGTH,
                        (size_t)(p - data),
                        1
                );
        vli = *p - '0' + 6;
 
        if (q - ++p < vli)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_TRUNCATED_GCP,
                        (p == q) ? 0                  : (size_t)(p - data),
                        (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                );
 
        /*
         * Validate the GCP with the "key" linter.
         *
         */
        strncpy(gcp, p, (size_t)vli);
        ret = gs1_lint_key(gcp, err_pos, err_len);
 
        assert (ret == GS1_LINTER_OK ||
                ret == GS1_LINTER_INVALID_GCP_PREFIX ||
                ret == GS1_LINTER_GCP_DATASOURCE_OFFLINE);
 
        if (ret != GS1_LINTER_OK)
                GS1_LINTER_RETURN_ERROR(
                        ret,
                        (size_t)(p - data),
                        (size_t)vli
                );
 
        p += vli;
 
 
        /*
         * Validate the existence of the six digit Offer Code.
         *
         */
        if (q - p < 6)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_TRUNCATED_OFFER_CODE,
                        (p == q) ? 0                  : (size_t)(p - data),
                        (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                );
 
        p += 6;
 
 
        /*
         * Validate that the Save Value follows its VLI and has the
         * corresponding length.
         *
         * Valid Save Value VLIs are "1" to "5".
         *
         */
        if (p == q)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_MISSING_SAVE_VALUE_VLI,
                        0,
                        (size_t)(q - data)
                );
        if (*p < '1' || *p > '5')
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_INVALID_SAVE_VALUE_LENGTH,
                        (size_t)(p - data),
                        1
                );
        vli = *p - '0';
 
        if (q - ++p < vli)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_TRUNCATED_SAVE_VALUE,
                        (p == q) ? 0                  : (size_t)(p - data),
                        (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                );
 
        p += vli;
 
 
        /*
         * Validate 1st Purchase Requirement follows its VLI and has the
         * corresponding length.
         *
         * Valid 1st Purchase Requirement VLIs are "1" to "5".
         *
         */
        if (p == q)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_MISSING_1ST_PURCHASE_REQUIREMENT_VLI,
                        0,
                        (size_t)(q - data)
                );
        if (*p < '1' || *p > '5')
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_INVALID_1ST_PURCHASE_REQUIREMENT_LENGTH,
                        (size_t)(p - data),
                        1
                );
        vli = *p - '0';
 
        if (q - ++p < vli)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_TRUNCATED_1ST_PURCHASE_REQUIREMENT,
                        (p == q) ? 0                  : (size_t)(p - data),
                        (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                );
 
        p += vli;
 
 
        /*
         * Validate the single-digit 1st Purchase Requirement Code.
         *
         * Valid values for 1st Purchase Requirement Code are "0" to "4" and
         * "9".
         *
         */
        if (p == q)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_MISSING_1ST_PURCHASE_REQUIREMENT_CODE,
                        0,
                        (size_t)(q - data)
                );
 
        if (*p > '4' && *p != '9')
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_INVALID_1ST_PURCHASE_REQUIREMENT_CODE,
                        (size_t)(p - data),
                        1
                );
 
 
        /*
         * Validate the existence of the three-digit 1st Purchase Family Code.
         *
         */
        if (q - ++p < 3)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_TRUNCATED_1ST_PURCHASE_FAMILY_CODE,
                        (p == q) ? 0                  : (size_t)(p - data),
                        (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                );
 
        p += 3;
 
 
        /*
         * Optional field 1: Additional rules and 2nd purchase
         * ===================================================
         *
         * This option field is indicated by the value "1".
         *
         */
        if (p < q && *p == '1') {
 
                /*
                 * Validate the single-digit Additional Purchase Rules Code.
                 *
                 * Valid values for the  Additional Purchase Rules Code are "0"
                 * to "3".
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_ADDITIONAL_PURCHASE_RULES_CODE,
                                0,
                                (size_t)(q - data)
                        );
 
                if (*p > '3')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_ADDITIONAL_PURCHASE_RULES_CODE,
                                (size_t)(p - data),
                                1
                        );
 
 
                /*
                 * Validate 2nd Purchase Requirement follows its VLI and has
                 * the corresponding length.
                 *
                 * Valid values for the 2nd Purchase Requirement VLI are "1" to
                 * "5".
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_2ND_PURCHASE_REQUIREMENT_VLI,
                                0,
                                (size_t)(q - data)
                        );
                if (*p < '1' || *p > '5')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_2ND_PURCHASE_REQUIREMENT_LENGTH,
                                (size_t)(p - data),
                                1
                        );
                vli = *p - '0';
 
                if (q - ++p < vli)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TRUNCATED_2ND_PURCHASE_REQUIREMENT,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                p += vli;
 
 
                /*
                 * Validate the single-digit 2nd Purchase Requirement Code.
                 *
                 * Valid values for the 2nd Purchase Requirement Code are "0"
                 * to "4" and "9".
                 *
                 */
                if (p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_2ND_PURCHASE_REQUIREMENT_CODE,
                                0,
                                (size_t)(q - data)
                        );
 
                if (*p > '4' && *p != '9')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_2ND_PURCHASE_REQUIREMENT_CODE,
                                (size_t)(p - data),
                                1
                        );
 
 
                /*
                 * Validate the existence of the three-digit 2nd Purchase
                 * Family Code.
                 *
                 */
                if (q - ++p < 3)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TRUNCATED_2ND_PURCHASE_FAMILY_CODE,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                p += 3;
 
 
                /*
                 * Validate that the 2nd Purchase GCP follows its VLI and has
                 * the corresponding length (plus 6, unless VLI is "9").
                 *
                 * Valid values for the 2nd Purchase GCP VLI are "0" to "6" and
                 * "9".
                 *
                 */
                if (p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_2ND_PURCHASE_GCP_VLI,
                                0,
                                (size_t)(q - data)
                        );
                if (*p > '6' && *p != '9')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_2ND_PURCHASE_GCP_LENGTH,
                                (size_t)(p - data),
                                1
                        );
                vli = (*p != '9') ? *p - '0' + 6 : 0;
 
                if (q - ++p < vli)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TRUNCATED_2ND_PURCHASE_GCP,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                /*
                 * Validate the GCP with the "key" linter.
                 *
                 */
                strncpy(gcp, p, (size_t)vli);
                ret = gs1_lint_key(gcp, err_pos, err_len);
 
                assert (ret == GS1_LINTER_OK ||
                        ret == GS1_LINTER_INVALID_GCP_PREFIX ||
                        ret == GS1_LINTER_GCP_DATASOURCE_OFFLINE);
 
                if (ret != GS1_LINTER_OK)
                        GS1_LINTER_RETURN_ERROR(
                                ret,
                                (size_t)(p - data),
                                (size_t)vli
                        );
 
                p += vli;
 
        }
 
 
        /*
         * Optional field 2: 3rd purchase
         * ==============================
         *
         * This option field is indicated by the value "2".
         *
         */
        if (p < q && *p == '2') {
 
                /*
                 * Validate 3rd Purchase Requirement follows its VLI and has
                 * the corresponding length.
                 *
                 * Valid values for the 3rd Purchase Requirement VLI are "1" to
                 * "5".
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_3RD_PURCHASE_REQUIREMENT_VLI,
                                0,
                                (size_t)(q - data)
                        );
                if (*p < '1' || *p > '5')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_3RD_PURCHASE_REQUIREMENT_LENGTH,
                                (size_t)(p - data),
                                1
                        );
                vli = *p - '0';
 
                if (q - ++p < vli)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TRUNCATED_3RD_PURCHASE_REQUIREMENT,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                p += vli;
 
 
                /*
                 * Validate the single-digit 3nd Purchase Requirement Code.
                 *
                 * Valie values for the 3nd Purchase Requirement Code are "0"
                 * to "4" and "9".
                 *
                 */
                if (p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_3RD_PURCHASE_REQUIREMENT_CODE,
                                0,
                                (size_t)(q - data)
                        );
 
                if (*p > '4' && *p != '9')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_3RD_PURCHASE_REQUIREMENT_CODE,
                                (size_t)(p - data),
                                1
                        );
 
 
                /*
                 * Validate that existence of the three digit 3rd Purchase
                 * Family Code.
                 *
                 */
                if (q - ++p < 3)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TRUNCATED_3RD_PURCHASE_FAMILY_CODE,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                p += 3;
 
 
                /*
                 * Validate that the 3rd Purchase GCP follows its VLI and has
                 * the corresponding length (plus 6, unless VLI is "9").
                 *
                 * Valid values for the 3rd Purchase GCP VLI are "0" to "6" and
                 * "9".
                 *
                 */
                if (p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_3RD_PURCHASE_GCP_VLI,
                                0,
                                (size_t)(q - data)
                        );
                if (*p > '6' && *p != '9')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_3RD_PURCHASE_GCP_LENGTH,
                                (size_t)(p - data),
                                1
                        );
                vli = (*p != '9') ? *p - '0' + 6 : 0;
 
                if (q - ++p < vli)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TRUNCATED_3RD_PURCHASE_GCP,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                /*
                 * Validate the GCP with the "key" linter.
                 *
                 */
                strncpy(gcp, p, (size_t)vli);
                ret = gs1_lint_key(gcp, err_pos, err_len);
 
                assert (ret == GS1_LINTER_OK ||
                        ret == GS1_LINTER_INVALID_GCP_PREFIX ||
                        ret == GS1_LINTER_GCP_DATASOURCE_OFFLINE);
 
                if (ret != GS1_LINTER_OK)
                        GS1_LINTER_RETURN_ERROR(
                                ret,
                                (size_t)(p - data),
                                (size_t)vli
                        );
 
                p += vli;
 
        }
 
 
        /*
         * Optional field 3: Expiration date
         * =================================
         *
         * This option field is indicated by the value "3".
         *
         */
        if (p < q && *p == '3') {
 
                /*
                 * Validate that the expiration date is in YYMMDD format.
                 *
                 */
                if (q - ++p < 6)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TOO_SHORT_FOR_EXPIRATION_DATE,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                memcpy(expiry_date, p, 6);
                ret = gs1_lint_yymmdd(expiry_date, err_pos, err_len);
 
                assert(ret == GS1_LINTER_OK ||
                       ret == GS1_LINTER_DATE_TOO_SHORT ||
                       ret == GS1_LINTER_DATE_TOO_LONG ||
                       ret == GS1_LINTER_NON_DIGIT_CHARACTER ||
                       ret == GS1_LINTER_ILLEGAL_MONTH ||
                       ret == GS1_LINTER_ILLEGAL_DAY);
 
                if (ret != GS1_LINTER_OK)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_EXIPIRATION_DATE,
                                (size_t)(p - data),
                                6
                        );
 
                p += 6;
 
                expiry_set = 1;
 
        }
 
 
        /*
         * Optional field 4: Start date
         * ============================
         *
         * This option field is indicated by the value "4".
         *
         */
        if (p < q && *p == '4') {
 
                char start_date[7] = {0};
 
                /*
                 * Validate that the start date is in YYMMDD format.
                 *
                 */
                if (q - ++p < 6)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TOO_SHORT_FOR_START_DATE,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                memcpy(start_date, p, 6);
                ret = gs1_lint_yymmdd(start_date, err_pos, err_len);
 
                assert(ret == GS1_LINTER_OK ||
                       ret == GS1_LINTER_DATE_TOO_SHORT ||
                       ret == GS1_LINTER_DATE_TOO_LONG ||
                       ret == GS1_LINTER_NON_DIGIT_CHARACTER ||
                       ret == GS1_LINTER_ILLEGAL_MONTH ||
                       ret == GS1_LINTER_ILLEGAL_DAY);
 
                if (ret != GS1_LINTER_OK)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_START_DATE,
                                (size_t)(p - data),
                                6
                        );
 
                /*
                 * If an expiration date has been set, then ensure that it does
                 * not preceed the start date.
                 *
                 */
                if (expiry_set && strcmp(start_date, expiry_date) > 0)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_EXPIRATION_BEFORE_START,
                                (size_t)(p - data - 8),
                                14
                        );
 
                p += 6;
 
        }
 
 
        /*
         * Optional field 5: Serial number
         * ===============================
         *
         * This option field is indicated by the value "5".
         *
         */
        if (p < q && *p == '5') {
 
                /*
                 * Validate Serial Number follows its VLI and has the corresponding
                 * length (plus 6).
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_SERIAL_NUMBER_VLI,
                                0,
                                (size_t)(q - data)
                        );
                vli = *p - '0' + 6;
 
                if (q - ++p < vli)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TRUNCATED_SERIAL_NUMBER,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                p += vli;
 
        }
 
 
        /*
         * Optional field 6: Retailer GCP/GLN
         * ==================================
         *
         * This option field is indicated by the value "6".
         *
         */
        if (p < q && *p == '6') {
 
                /*
                 * Validate that the Retailer GCP/GLN follows its VLI and has
                 * the corresponding length (plus 6).
                 *
                 * Valid values for the Retailer GCP/GLN VLI are "1" to "7".
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_RETAILER_GCP_OR_GLN_VLI,
                                0,
                                (size_t)(q - data)
                        );
                if (*p < '1' || *p > '7')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_RETAILER_GCP_OR_GLN_LENGTH,
                                (size_t)(p - data),
                                1
                        );
                vli = *p - '0' + 6;
 
                if (q - ++p < vli)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_TRUNCATED_RETAILER_GCP_OR_GLN,
                                (p == q) ? 0                  : (size_t)(p - data),
                                (p == q) ? (size_t)(q - data) : (size_t)(q - p)
                        );
 
                /*
                 * Validate the GCP/GLN with the "key" linter.
                 *
                 */
                strncpy(gcp, p, (size_t)vli);
                ret = gs1_lint_key(gcp, err_pos, err_len);
 
                assert (ret == GS1_LINTER_OK ||
                        ret == GS1_LINTER_INVALID_GCP_PREFIX ||
                        ret == GS1_LINTER_GCP_DATASOURCE_OFFLINE);
 
                if (ret != GS1_LINTER_OK)
                        GS1_LINTER_RETURN_ERROR(
                                ret,
                                (size_t)(p - data),
                                (size_t)vli
                        );
 
                p += vli;
 
        }
 
 
        /*
         * Optional field 9: Miscellaneous
         * ===============================
         *
         * This option field is indicated by the value "9".
         *
         */
        if (p < q && *p == '9') {
 
                /*
                 * Validate the single-digit Save Value Code.
                 *
                 * Valid values for the Save Value Code are "0" to "2" and "5"
                 * to "6".
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_SAVE_VALUE_CODE,
                                0,
                                (size_t)(q - data)
                        );
                if (*p != '0' && *p != '1' && *p != '2' && *p != '5' && *p != '6')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_SAVE_VALUE_CODE,
                                (size_t)(p - data),
                                1
                        );
 
 
                /*
                 * Validate the single-digit Save Value Applies to Item value.
                 *
                 * Valid values for Save Value Applies to Item are "0" to "2".
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_SAVE_VALUE_APPLIES_TO_ITEM,
                                0,
                                (size_t)(q - data)
                        );
                if (*p > '2')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_SAVE_VALUE_APPLIES_TO_ITEM,
                                (size_t)(p - data),
                                1
                        );
 
 
                /*
                 * Validate the existence of the single-digit Store Coupon
                 * Flag.
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_STORE_COUPON_FLAG,
                                0,
                                (size_t)(q - data)
                        );
 
 
                /*
                 * Validate the single-digit Don't Multiply Flag.
                 *
                 * Valid values for the Don't Multiply Flag are "0" and "1".
                 *
                 */
                if (++p == q)
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_MISSING_DONT_MULTIPLY_FLAG,
                                0,
                                (size_t)(q - data)
                        );
                if (*p != '0' && *p != '1')
                        GS1_LINTER_RETURN_ERROR(
                                GS1_LINTER_COUPON_INVALID_DONT_MULTIPLY_FLAG,
                                (size_t)(p - data),
                                1
                        );
 
                p++;
 
        }
 
        /*
         * Report excess data that has not been handled as an optional field.
         *
         */
        if (p != q)
                GS1_LINTER_RETURN_ERROR(
                        GS1_LINTER_COUPON_EXCESS_DATA,
                        (size_t)(p - data),
                        (size_t)(q - p)
                );
 
        GS1_LINTER_RETURN_OK;
 
}