Regular expression structure for matching payment references

  • 15/07/2025
  • 3 minutes to read

A regular expression (regex) is a sequence of characters that defines a specific pattern used to search patterns in text. Regex is commonly used for pattern matching, input validation, text transformation, and querying. When working with payment references in Continia Banking, regular expressions help define and validate the structure of the incoming reference strings. This is especially useful when dealing with various standardized formats such as FIK or SCOR references.

This article describes how these regular expressions work and what each part does.

Example 1: FIK reference

The following example provides a pattern that matches the references exactly.

Sample string:

71/000000001032259

Regex pattern:

^71\/(?!0{14})\d{14}\d$

Explanation:

PatternDescription
^Anchors the expression to the start of the string.
71/Matches the literal prefix 71/, which is fixed.
(?!0{14})A negative lookahead that ensures the next 14 characters are not all zeroes.
\d{14}Matches exactly 14 digits.
\dMatches one additional digit, usually a check digit.
$Anchors the expression to the end of the string.

This pattern ensures:

  • The reference starts with 71/.
  • The main body isn’t all zeroes.
  • The total number of digits after the slash is 15.
  • The string matches the expected structure exactly - no more, no less.

Example 2: SCOR reference

The SCOR reference begins with RF, followed by 2 digits, then up to 21 alphanumeric characters. The following pattern enforces the required RF prefix and check digits, and allows a flexible range of characters afterward.

Sample string:

RF18539007547034

Regex pattern:

^RF\d{2}[0-9A-Za-z]{1,21}$

Explanation:

PatternDescription
^Anchors the expression to the start of the string.
RFMatches the literal characters RF.
\d{2}Matches exactly 2 digits.
[0-9A-Za-z]{1,21}Matches between 1 and 21 alphanumeric characters (digits and letters, upper or lowercase).
$Anchors the expression to the end of the string.

This pattern allows flexible but valid SCOR references by:

  • Requiring the RF prefix and 2 check digits.
  • Allowing a wide range of characters afterward.
  • Limiting the length to a maximum of 21 characters.