If I am going to be working with a large number of items that might be
subdivided into various categories with various options per category, the
first thing I do is try to organize my project with a block diagram. I
define my objective, then start with step 1 of actions needed to reach the
objective. by the time I have developed the block diagram it is pretty
evident where I will need controls and I can decide what types of controls
and which category of items or options to load into those controls. It is
much easier to make decisions and describe the problems with the diagram of
the steps to be completed.

" wrote:

I have a vba program that uses a userform for selecting parts in table
- the parts are grouped into 40+ groups with 2 levels of sub groups -
how do I keep the first level unique? As well as the second level?
For example 8000 parts into 40 groups - one group called bycles,
second group - mountian bikes, third group - size of.....