I have personally seen, and I think I even filled out, an SF-171. Harrowing experience, worse than being probed by aliens. I cannot remember actually filling it out because it was so horrible, and I probably had no chance of getting the job. I think this one might have been for a federal judicial clerkship where during the interview the old salt who ran the office mentioned how it is a great job for a woman. (I am a white man.) The experience of filling out the form has been blocked by my memory to protect me from the trauma.
I clearly remember filling out the governemnt resume on usajobs.com, which resume is an on-line successor to the SF-171 monstrosity. It dies in 3 or 6 months if you do not use it or update it. I used it to apply for a half-time GS-11 job right around the corner from me, but some HR person in Norfolk, VA decided I did not have the minimum prereqs to even let the nice folks around the corner from me see my resume.
Pancake. Bunny. Et al.