The fundamental goal of documenting bloodstain patterns is to accurately depict the patterns as you found them. Your notes should contain a detailed description of the physical characteristics of the patterns including size, distribution, location, shape, and physical features.

When taking notes, remember to use terms like “reddish-brown stain,” “visually consistent with blood,” “bloodlike,” or some other term until laboratory analysis confirms that it is blood. These physical description details become important when classifying patterns into categories and will help to supplement your photographs. There are several classification systems used in the field of bloodstain pattern analysis. One of the most practical was developed by Stuart H. James, Paul E. Kish, and T. Paulette Sutton. In this taxonomy, patterns are categorized based upon their physical appearance and the mechanism that created the pattern. This is a conservative and holistic approach that uses the three primary groups of Passive, Spatter, and Altered as well as several subcategories under each group.

From: Documenting Bloodstain Patterns Through Roadmapping by Daniel R. Winterich