File with an .ACL extension contains a list used for purpose of automatic writing and grammatical error correction in Microsoft Office programs, utilised by the AutoCorrect tool. It is a common file for all MS Office programs on a given computer for the user, in a specific language.

ACL files can be changed while using them within the program with the option to add a given word or structure to the dictionary, this should not be performed outside the dictionary – manually. There is a possibility to transfer ACL files of a user between older and newer versions of the Office Suite.