How lock set on file is affected by check out

When check out operation is performed on file, the lock set will be that of the check out option specified. It may lead to some not entirely obvious consequences.

Obvious example
1) No lock on file prior to check out
2) After check out is performed with lock option other than "None"("Check-out" or "Check-in" lock), the file is editable and has changes "Lock,Edit" associated with it (in "View Pending Changes" window)

Not so obvious example
1) Lock on file prior to check out ("Check-out" or "Check-in" lock)
2) After check out is performed with "None" lock option, the file is editable and has change "Edit" (in "View Pending Changes" window)
That is, previously set lock level was essentially removed (demoted) by using check-out option.

So lock level may be either promoted or demoted by check out operation (the situation occurs only in case lock is owned by user performing check out or user has admin permissions for locks). Personally I think that is the thing to watch for or at least to be aware of.

As Microsoft explained in their answer, locks are affected only by explicit check outs; implicit check outs (for example, when auto check out on edit is enabled) are not affected.