Syntax definition
The syntax definition can be browsed online:
The syntax definition of the PHP versions identify which constructs there are and which productions are allowed.
API documentation
The PHP-front library contains many useful strategies, there is documentation for most of the strategies:
Projects based on PHP-front
These two guides should help you with starting your own project based on PHP-Front:
Development
If you want to extend/adapt/improve PHP-front, please look at the
generic development instructions in order to set up your workbench.