token.gm_name
The variable token.gm_name allows programmatic querying and setting of the token's GM Name (the second text field in the screenshot of the Edit Token dialog).
Examples
Getting the Token GM Name
[h:secretName=token.gm_name]
GM's Name: [secretName]
Outputs the value of token.gm_name.
Setting the Token GM Name
[h:token.gm_name = "Soldier"]
Sets the value of token.gm_name to "Soldier."