.OCA File Extension

Accompanying file saved with Visual Basic custom control (.OCX) files; contains standard descriptions of objects, properties, and methods used by OLE Automation; created automatically by Visual Basic and given the same name as the custom control except for the file extension.

OCA files are binary files that serve as both extended type libraries and a cache for OCX files. If an OCA file is deleted, it can be rebuilt by Visual Basic, but will take extra time.