How does gvim define the shortcut ctrl+; ?

  question, vim

For example, ctrl+ is defined under gvim; To turn on or hide the shortcut keys for NERDTree, the following are:

map <C-;  > :NERDTreeToggle<CR>

It is not recognized by gvim, please understand the classmates, thank you very much.

Write a semicolonmap <c-; >There is no problem
However, vim cannot capture it<c-; >, the user inputctrl+;Identified as;The