Validation question

I have a table where column A looks like:

1. o.c. < 700 mm
2. <empty cell>
3. o.c. >= 700 mm
4. <empty cell>
5. o.c. < 700 mm with...
6. <empty cell>
7. o.c. >= 700 mm with...
8. <empty cell>

I want to create a validation (ie. a drop down list) that only includes cells that are filled with information (ie. do not want blank cells).


Thank you

Any good solution to this one?

Users will have multiple similar drop-down lists, which are generated from multiple tables that are already created. Base on these different inputs, my spreadsheet will search for the proper values from these tables and perform different calculations.

Hope I am clear.


Thanks

It's not exactly a simple LOOKUP(). It's more like LOOKUP() within LOOKUP() within LOOKUP(). I will show you one of the tables just for your information.

What I really want is to create a drop-down list where I can specific a range from my existing tables. Yet, I DO NOT want any blank cells (existing tables have blank cells within the range that I want) to be included. See attachment.

Thanks