The load_table_model function can be called with an identifier and a filename and path argument, in which case all the default arguments will be used depending on the file's type. In both cases, the image or table will be read into a model that can be combined arithmetically with the source model. In the table case, the user can specify which columns to read from the file by their column names in the order as they correspond to the data arrays in the data set. If no columns names are present, defaults will be assigned. (e.g., "col1", "col2", ...) The default data set, Data1D, uses the order: x, y, staterror, syserror for data arrays. The dependent array from the image or table will be used as the table model values. Data set IDs can be integers or strings; in the latter case a string can denote useful information about the data (e.g., whether it is your source, PSF, or exposure map data set).