Mathematical Steps of the Check Character System

The check characters in characters 19 and 20 of the LEI code verify formatting accuracy [1]. To validate an LEI using the ISO 7064 Mod 97-10 algorithm, follow these mathematical steps:

  1. Convert all letters in the 20-character string to numbers where A = 10, B = 11, C = 12, ..., Z = 35.
  2. Move the check digits (characters 19 and 20) to the end of the newly generated numerical string.
  3. Compute the modulo 97 of the resulting integer.
  4. Assert that the remainder equals exactly 1. If the remainder is 1, the format is valid [1].

Our client-side validator implements this algorithm in pure Javascript to perform instant validation checks on target LEIs without querying external APIs.