Here are the areas that should be documented (see gittrac #2815).  I re-ordered them somewhat to make the list more logical in terms of related functionality.

*: condor_submit_dag/scheduler universe startup
*: DAG file parsing
*: {wiki: RescueDag Rescue DAG/condor_rm of DAGMan}
*: recovery mode/condor_hold/condor_release
*: proper ordering of jobs/scripts (ready queue, etc.)
*: implementation of PRE/POST script semantics
*: reading the user logs
*: deciding when the DAG is finished
*: ABORT-DAG-ON
*: final node
*: node variables
*: nested DAGs
*: splices
*: node retries
*: submit retries
*: DAG-wide throttles (maxjobs, maxidle, maxpre, maxpost)
*: category throttles
*: depth-first DAG traversal
*: node priorities
*: halt file
*: NOOP nodes (at DAG level)
*: multi-job clusters
*: strict warnings
*: DIR on nodes
*: node status file
*: jobstate.log file
*: dot file
*: Stork support