This file will describe, in brief, the functionality of the TwoResSubsetter code. This code can be used to spatially subset and/or subset a specified list of Scientific Data Sets (SDS). This code can be used on HDF files that contain Geolocation data at one resolution, but has SDS at the resolution of the Geolocation, and a higher resolution (For example, if the Geolocation is at 5km resolution, but there are SDS at 5 and 1 km resolutions.). These include the L1B data, MOD05, MOD06, and MOD35. The code might be applicable to other cases, but these are the only cases to have been tested. Specifically, this code is used to create an HDF file that contains a defined set of Scientific Data Sets (SDS), whose points are a defined box around an inputted Latitude and Longitude point. The code searches through a list of HDF files and only creates a new file if the coordinates are within the desired Lat/Lon box. The list is generated by specifying one or more input directories, thus allowing one to subset a days worth or a months worth of granules. In addition, the code can handle multiple Lat/Lon points, and allows for a prefix to be attached to the new HDF file for identification purposes (ex. you can name a certain Lat/Lon point ALEXEGT for Alexandria Egypt, such that the new HDF file will be named ALEXEGTMODXY___.hdf). Additional functionality include a flag to perform, or not, the spatial subsetting and an option to include all SDSs in the new HDF file. For more detail please see the documentation text files and the summary given at the top of the TwoResSubsetter.f90 file and the PERL script. Please refer to the 11HowToRunProgram.txt and 11Parameters.txt text files for more information. If your datasets have only one, please use the SnglResSubsetter code, or contact Eric Moody (Eric.Moody@GSFC.NASA.gov) for an appropriate code.