This command can also be used on output photometry files to merge them together into one file, for later use by FITSTAR. In this mode, the program will prompt for a file name, read the stars in from this file and output them to a new file, then ask for a new input file, from which to append the results onto the original output file. This can be used, for example, to merge all observations of standard stars from multiple frames into one file. The NORM keyword will normalize all the measured magnitudes to a standard exposure time, assuming the exposure is stored in the data file.