The awl is used to mark points on the inside of the block or pattern, by piercing a hole through the cardboard or paper. The resulting hole is referred to as a "drill hole". These drill holes indicate the placement of the dart point, pocket placements, buttons and buttonholes, and other interior features that need to be marked onto the fabric from the pattern.
The example below illustrates where the awl is used to mark the Bodice Front block. The Bust Point and Dart Point are inside the pattern and the Awl is punched through all three points. The patternmaker can then put a pencil tip through those holes and mark these points on the paper or cardboard underneath.
The awl is pushed through the Bust Point and the two Dart Points to create holes.
When creating patterns with this block, a pencil can be placed in the holes to mark the points on the paper underneath.
Note: Related Tool
For the tool that is used to mark the the edges of the block - see the Pattern Notcher.