The $CLAW/amrclaw directory contains a version of Clawpack that uses adaptive mesh refinement (AMR).
See Specifying AMRClaw parameters in setrun.py for a description of the run-time parameters needed by AMRClaw and how to set them.
The refinement strategy and criteria are described in AMR refinement strategy.
Several examples can be found from Applications gallery, look for ones with an amr subdirectory.
The sections below detail many components of the library $CLAW/amrclaw/2d.
This describes most of the entries in the common block, call.i.