这是ASTM F 963-08 A4对string的定义:
A4.2.5 strings—long slender flexible material usually consisting
of several strands (as of thread or yarn) woven or
twisted together, usually used to bind, fasten, tether, or tie. This
does not include string when used, for example, for hair on a
doll.
下面是豁免的条款:
A4.3 Exemptions
A4.3.1 Strings, paper, and ping-pong balls.