Unclear function when using bump

[lennart]

When you select a plane > Bump > tab, you get an entry window. The first entry is the size of bump. But what is the %? A bevel? Maybe a (short) description would help 

   

[micheus]

But what is the %? A bevel? Maybe a (short) description would help 

That represents a percentage value (%).

When you starts the command, before you start to bump the faces, the new edge loop is placed in an "arbitrary" distance from the selection (it's computed).
That distance is equivalent to 100% (the value you see on the information line on top of Geometry window or in the input dialog). By increasing that you are going to multiply that initial distance by the % factor. This way, if that "arbitrary" value is 0.05 and your input is 200 (%) then the edge loop is going to be 0.1 distant from the selected edge loops.



If you need precision where that edge loop should be placed I would recommend you to just bump and set that percent to 0.0. Then, you can use Slide to place it on a specific distance.