Here is an example of how Tekla Structures uses the Recognizable distance setting in integrated dimensioning. If you set value for Recognizable distance on the General tab, and the asymmetry of the parts is smaller than the distance you entered, Tekla Structures represents it using a dimension.
This setting is used, when the Internal dimension is set to Necessary. Recognizable distance dimension is not necessarily needed, if the part can be assembled correctly without it.
A typical example is a rectangle that is almost as long as it is wide.