The Woodland Pattern, also known unofficially by its colloquial moniker of M81, was the default camouflage pattern issued to United States soldiers, Marines, airmen, and sailors from 1981, with the issue of the Battle Dress Uniform, until its replacement around 2006. It is a four color, high contrast disruptive pattern with irregular markings in sand, brown, green and black.
Woodland pattern is identical to ERDL, but is printed from an enlargement of the original. The ERDL pattern was enlarged and the borders of the were re-drawn to make them less regular. Part of the earlier pattern was left off the later pattern because the enlargement made them no longer fit on the width of the bolt of cloth. The pattern does not repeat horizontally across the width of the bolt, but only vertically along its length.
The effect of enlarging the pattern was to make the pattern more visible at a distance, avoiding "blobbing", where smaller areas of color seem to blend into larger blobs. This also gave the pattern a higher contrast, making it stand out more sharply at close distances and defeating the camouflage effect at closer range. Digital and Flecktarn camouflage patterns resolve this problem by using a range of blob sizes to give a similar effect whatever the distance.
These changes reflected a shift in the tactical focus of the United States military from an extremely close-range war in Vietnam to a longer-range battlespace on the fields of Europe.
MOPP suits still feature the woodland pattern.
In the U.S. Army, the Woodland Pattern BDU was replaced by the digital Universal Camouflage Pattern (UCP) found on the Army Combat Uniform, which was invented in 2004 and introduced in 2005. UCP itself will be replaced by Scorpion W2 (OCP) in 2019.