Michael
I guess the first question is which type of Data Collector - are we talking SCS900 / Siteworks or Access or something else? As people have already stated, the SCS900 / Siteworks system can take the Points in a DXF file and the Layers are automatically carried in that process, allowing you to turn the layers of points On / Off in the field. If you are using the CSV files for SCS900 / Siteworks, then there is no support for Layers in that format as it is simply P,N,E,Z,D format - so unless you use the Point Number or Description field for the Layer name and then filter down by that field on the controller there is nothing there that you can do. If you are using Access - I would have to ask my colleagues on the Access side of the fence as to what they can take in terms of point files to read into Access and have some form of Layer Control. As someone pointed out, you can create a custom Export format that includes the Layer Attribute so you could output P,N,E,Z,D,Layer and if that attribute can be used by the field software then that is likely your answer. If SCS900 / Siteworks, you could use Notepad to Merge ",D,Layer" into something like D-Layer so that the Layer names are carried to some degree, but I don't believe SCS900 / Siteworks have any tools to use the Layer field if it is there - I will check as that ma have been added I guess.
Alan