Custom user properties from DB table?

Hello--

I was curious if anyone has added a custom select menu for users to select from as part of the user registration process.  I have a database table that I want to use as the source for the select menu.  I started to dig into the source code of the page and can probably get it into the page but I am worried about not finding all the other places that I need to "fix" in order for this to work throughout the site if I got that route.  Any ideas/suggestions?

If you are talking about like City, State, Country, etc these are predefined
values you can edit at Admin > Settings > Predefined values  ..... 

HTH

.

I wasn't but I think that might work.  Is there anything that defines what all the different extra parameters do?

Click on the block in Admin > settings > Builders and you can configure about anything you need  ..... 
Use an existing block as a template or guide  ..... 

HTH

.