Not sure I totally understand the Question - but if you have a Layer or Layers of data and you want to select all data that has an Elevation Range between one value and another then you can do that with Advanced Select
Select all data you want to make the sub selection from
Advanced Select
Select Multiple Data Types
That have this property - Elevation
Greater than (the minimum value - if you want 100.00 and greater then enter 99.999) or select Geeater than or Equal To 100.000
Apply - this selects all data in your selection that is >100.00 elevation. This is a new Current selection to work from
Now select
Multiple Types
That have this Property = Elevation
Less Than or Equal to (the higher value of the range ) eg 120.00
Now what is selected is the data that falls between the Low and High Value you entered
Advanced Select with all its tools allows you to find data in a data set that no other software that I know of can even get close to - I have heard from many users that this is one of the "most awesome tools in TBC" that allows you to get at the data - while some of the UI could be enhanced for sure - the tool really allows you to do this kind of thing quickly and easily once you know how
Alan