Every STEP Exchange file has a header with some information fields. You can view this information by selecting the File | File Header menu entry, or typing the Ctrl+H keyboard shortcut. A dialog window will open showing the contents of the header.
The most important field in the header information is the schema. This indicates the STEP application protocol or other standard used to write the contents of the exchange file. Common schemas are "CONFIG_CONTROL_DESIGN" for AP203 and "AUTOMOTIVE_DESIGN" for AP214. There is a timestamp indicating when the file was created, as well as fields for identifying the system that generated it.
Finally, there are open ended fields for describing the contents of the file, identifying the person who generated it, as well as the organization that they work for.