PHP Dev Reimplements EU E-Invoicing Rules to Avoid XSLT 2.0 Trap

A PHP developer building Croatian e-invoicing compliance found PHP's XSLTProcessor only supports XSLT 1.0, while the official Schematron validation file requires XSLT 2.0. To avoid a network dependency or compiled extension, he reimplemented 62 validation rules in PHP. The approach is portable but requires careful testing against the original Schematron to catch subtle bugs like the one he discovered in credit note validation.