This template is intended for categories in the form "Category:Terms with manual transliterations different from the automated ones/<language code>" it takes the language code as its only parameter.

Using {{trmandiffcat|grc}} in Category:Terms with manual transliterations different from the automated ones/grc makes the category a hidden one and adds to it the following categories:

[[Category:Terms with manual transliterations different from the automated ones|grc]]
[[Category:Ancient Greek entry maintenance]]