The easiest way to learn how to lay out a definition text file is to browse through a definition file which you have decompiled from an interpretations file supplied with Solar Fire. These will be wherever you have saved the definition file to. Any definition files supplied by Solar Fire will be found in the "Interpretations" subfolder of the "Solar Fire User Files" folder. (see Decompiling)
In any input file there are four types of lines which may legally appear. These are comment lines, directive lines, keyword lines and text lines.