As part of a basement remodel, some of the old (1940s) plumbing is being changed around. In order to move some of the waste drain from the side bathroom toilet, there were some 90 degree elbows put in. Are you always supposed to use less than 90 degree elbows for toilet waste, or are regular elbows sufficient?
There isn't any rule/code against it. Once you hit 135 degrees you are required to have a clean-out - if they look. I would personally use two 45s or a long-turn 90. If you buy a short 90 the world won't explode but you will be pumping your stuck toilet more.