Map segments - reusability

Prax Kan

This might be a noob question - I've never used map segments, and documentation on it is almost non-existent.

Usecase:
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We have 3-4 procedures that have a form segment that basically show the same information, and the same variables. While reading up on map segments, it seemed like a good candidate for using map segments. 

Questions

If I create a library, and a map segment inside it with the form segment (and variables) - what happens if

a) I use this library in a procedure but don't pull the map segment onto the "parent map". Does it still create the segment's variables in the parent procedure ? [aka does it create database columns simply by the act of adding a library with segment, or does it create columns when the segment is actually USED in a map]

b) I use this library in the usecase procedures, delete the existing "local" form segment and use the library's segment in the forms instead
     - Will it delete and recreate the columns for variables (ie, will I lose all existing variable data for in flight/archived folders)
     - Will it retain the data and just use variable references from the library's segment

Prax Kan

The answer seems to be (tried this out for myself using test procedures and libraries)

a) It doesn't create variables simply by association. Only USING the map segment from a library creates variables (the act of dragging it onto a map)

b) Data is retained, it doesn't drop and recreate columns. As long as variable names are the same it just switches reference to the variables in the map segment (essentially they become variables in the procedure, the map segment is the reference I believe)...

Eitherway this seems like the best case scenario I was hoping for