There are three components to the documentation: historic research and narrative, measured drawings, and photographs. Each of these is described in detailed guidelines that describe what information should be recorded and how it should be done. HALS is intended to be a comprehensive, scholarly record that provides a permanent detailed record of the landscape.
There are four levels of HALS documentation:
large-format photographs, long-format report, and measured drawings
large-format photographs, long-format report, and reproductions of original drawings (must adequately, concisely, legibly represent the current landscape)
large-format photographs, short-format report, and optional but preferable sketch plan
short-format report with optional sketch plan and optional digital photographs on a figure page at the end of the report
Critical need, time, and resources will all factor into your decision of which level to follow. The short-format report is typically two to four pages long. The long-format report is prepared using the standard HALS outline format.