drive:\myapp drive:\myapp\data drive:\myapp\reports etc.You could also have the app check for the data in your default directory upon start up and if not found, prompt the user to specify where it was installed. Then store this value to a table and reference it each time the app is run before checking for the data. This will cause the user to find the location only once and again only when they have moved the data to a different directory.
sele 1 use ref.dbf set path to ref.mypath IF file('somefile.dbf') ELSE lcpath = getdir() set path to lcpath sele ref.dbf replace mypath with lcpath ENDIFYou could use several more complex solutions if these don't work for you by setting up a configuration file which will check for and prompt for data directories.