Validation rules are syntactic and semantic criteria applied to the data in form fields. These rules are used to police data input to ensure its uniformity and compliance with underlying database formats and constraints. In the case of electronic forms the automated validation subroutines are also designed as a defence mechanism against accidental or malicious user action. These circumventions or failures in code execution have the potential of revealing otherwise hidden attributes of encoded data with its relational structure, embedded assertions or judgements.