2426526 - How to use a Business Rule to apply a Format/Regular Expression to a Field

How can I set up a business rule, to apply a format/regular expression to a field within EC.
For example:

• only digits can be entered in a string field.
• only alphabetic character can be entered in a sting field.
• only latin characters can be entered into a string field
• only a certain format can be enter, for example, 1 alphabetic character, followed be 4 digits.

Format, Business Rule, Regular Expression, Number, Digit, Alphanumeric, reg-ex, Matches(), Format(), Matches, String to be checked , KBA , LOD-SF-EC , Employee Central , LOD-SF-MDF-RUL , Custom Oject based Business Rules , How To