(This functionality is available with the Transformations module)
The Save Transformation command is available from the Transformations / Co-ordinates menu. It is used to save the currently loaded coordinate transformation to a .trp file.
You may save as many .trp files as you wish and they can be reloaded for use in any project using the Transfomations / Co-ordinates / Load Transformation command.
To create a new .trp file, first use Transformations / Co-ordinates / Define Transformation to load the new transformation. Then use this command to save it as a trp file.