# Which policy to complete an answer made by someone else ?

What is the general policy for completing an answer from an other user ? Should I prefer to start an other answer, just saying "As user:xxx said, blabbla, BUT I would like to add blabla..." or should I edit the previous answer, with the possibility to severely annoy its author ? After all, that's her/his answer... so is it well accepted to edit the others' answers ?

For instance, part of the answer should be wrong. Should I delete this part by myself, or make a comment to the author ? (I obviously prefer the second option, but the first one, if it become more accepted, could be time saving I believe).

For instance, an answer could be full of doubtful remarks like "I believe that $x=y$... ", but I know this is for sure. Should I edit the answer such that only "$x=y$" appears ?

This has been asked multiple times on the main meta. In this case I'll just copy my answer over there.

Examples:

Factors affecting torque and RPM of a motor

How can one imagine curled up dimensions?

Penetration versus Frequency

Will an emf be induced across the ends of a stationary metal rod placed in a time-varying magnetic field?

In the case of wrong answers (or parts of answers), leave a comment. Try not to make radical changes in edits -- you can tell the OP in a comment to make them himself.

• Thanks for your answer. I indeed forgot to check on the SO meta. Sorry for the repeat. Thanks again. – FraSchelle Jun 13 '13 at 14:23
• Even adding a paragraph to an existing answer is something I would consider a radical edit, if it didn't actually come from the OP. – David Z Jun 13 '13 at 18:23