Pitch Pocket Wood Irregularity : An opening extending parallel to the annual growth rings that contains, or that has contained, either solid or liquid pitch
NFPA 1931 Standard for Manufacturer's Design of Fire Department Ground Ladders, 2004 ed. https://www.nfpa.org/assets/files/AboutTheCodes/19 32/1932-A2004-ROP.pdf, (Std: Mfg Design of Fr Dept Gr Ladr - Amer) {419 NFC}