Everett:
I have a Schneiderman Refill here that says "D1" on it. If your refill is the same as mine. It is a cheap version of the Schmidt 888 rollerball refill.
EDIT: Just saw Pierre Belvedere! PB's D1 refill is a ball point and IIRC had something wired about it that will not allow a Parker to work. I'll try to find you a link.