A container file should have an .spg extension. It is used for listing the paths of the .parser source files that belong to parser project.
| container‑file | → | project qualified‑id ; container‑file‑content |
| container‑file‑content | → | source‑file* |
| qualified‑id | → | identifier (. identifier)* |
| source‑file | → | source file‑path ; |
The following keywords may not be used as identifiers in the container file:
| container‑file‑keyword | → | project | source |