Class Diagrams, Operation Specification - What are "Lower and Upper"?

Question

I am unsure of the meaning of Lower and Upper as seen in the screenshot below.

I'm using Visual Paradigm to document my design. I've searched their documentation for answers but could not find any.

Can someone explain to me the meaning of those input fields?

Answer 1

These parameters are intended to show the operation's multiplicity - the upper and lower boundary. 1..* here will be set as lower=1, upper=*. The problem is, that there are some bugs and you can't either see this multiplicity on the diagram, or have it engineered in the code.

The bug is not repaired till now. ( http://forums.visual-paradigm.com/posts/list/6652.html)

Answer 2

Upper and Lower are multiplicity of return parameter of operation you define in your example. It is normally not set to operation directly, but to operation's return parameter. Operation can have zero or one return parameter.