Need signature of binary Grasshopper file for file recovery

My Bootcamp Windows partition has become corrupted and I’m trying to recover my Grasshopper files using PhotoRec. It doesn’t support binary Grasshopper files but you can add your own signature with an offset and a series of bytes in hexdecimal format e.g.

gh 0 0x50686f746f46696c74726520496d616765

Does anyone knew a series of bytes that is constant in all Grasshopper files? I’ve looked at a few files in a visual binary diff programme but the only constant is the first byte which is too general.