R help - Mar 2003 - Summary: length() "ain't misbehavin'" after all

I asked why length(byyr$cnd95[byyr$cnd95=="tr"]) was counting NA's
as well as "tr"s.
Thanks to Brian Ripley, Uwe Ligges, Ott Toomet, Marc Schwartz, and Thomas Lumley
for
their help.

Two solutions were to replace my call with

length[byyr$cnd95 %in% "tr"] or with sum(byyr$cnd95 == "tr",
na.rm=TRUE)

and there were variations on those themes.

Thanks again.
Dave