You may be going down the wrong path:
* Table Field values MUST be atomic (the First Normal Form), i.e. each one
storing a single item of data, NOT a list of items.
* Multi-Select ListBox always has Null value. You will need to use VBA
code to manipulate the selected rows into a list.
* Queries are probably possible but certainly NOT going to be efficient as
they could be if your Table Structure is properly designed and implemented
according to the Relational Database Design Theory (RDDT).
* If you look at it this way: you are trying to combine items into the
single list and then later trying to break down the list to items (in a way)
in your queries for selection / further processing. It certainly much more
efficient to store each item separately (according to RDDT) and use them
accordingly.
* There are other problems with storing a list of items in a single Field.
* See the thread "Creating tables" started by "dumbo" in the newsgroup
"microsoft.public.access" on 5 November 2003 14:46 (my date / time, GMT +
11:00) on RDDT.