From: Rabbi Moshe Sofer
To: Rabbi Moshe Perles
The Chasam Sofer rules that the hundred signatories for a Heter Meah Rabbonim must be ordained scholars bearing the title Moreinu but need not be formal communal rabbis, and unmarried students may not be counted. The three-country requirement refers to regions with distinct communal identities — Poland/Galicia, Hungary, and Austria each qualify separately despite sharing Habsburg rule — and while equal division into thirds is the ideal, the established practice does not require exact thirds. He also defends his earlier position on appointing agents to deliver a get upon the wife's recovery from insanity.
Source: Shu"t Chasam Sofer EH I §4