Well, bless.  “Pocket handkerchief” has its own OED entry – not hyphenated – and means not only a handkerchief for carrying in the pocket (where else might one carry a handkerchief?), but a small area (as of land), or a small, light sail such as a jib or topsail.

• 02.020 and found he had come without a pocket-handkerchief!
• 02.024 and I have left my pocket-handkerchief behind,
• 02.025 You will have to manage without pocket-handkerchiefs,
• 02.027 He had brought a lot of pocket-handkerchiefs,
• 12.008 without a pocket-handkerchief
• 12.008 He had not had a pocket-handkerchief

“pocket handkerchief, n.” OED Online. Oxford University Press, June 2015. Web. 24 July 2015.