[texhax] argument of \vector

[Edgar Goodaire]

Friends:
Kopka and Daly (third edition), p. 159, says that the arguments to the  
\vector command in the LaTeX picture environment are the same as those 
of \line, namely \pm 0, ..., 6 (p. 158).  But while
LaTeX processes \line(5,-2){10} just fine, it spits back 
\vector(5,-2){10} complaining about a bad \vector argument.   Is 
Kopka/Daly incorrect?  I am using MiKTeX.  .................Edgar