=item Functions for filehandles, files, or directories
--X, chdir, chmod, chown, chroot, fcntl, glob, ioctl, link,
+C<-X>, chdir, chmod, chown, chroot, fcntl, glob, ioctl, link,
lstat, mkdir, open, opendir, readlink, rename, rmdir,
stat, symlink, umask, unlink, utime
specified FILEHANDLE, using the system call write(2). It bypasses
stdio, so mixing this with prints may cause confusion. Returns the
number of bytes actually written, or undef if there was an error. An
-OFFSET may be specified to place the read data at some other place than
+OFFSET may be specified to get the write data from some other place than
the beginning of the string.
=item tell FILEHANDLE
=item vec EXPR,OFFSET,BITS
-Treats a string as a vector of unsigned integers, and returns the value
-of the bitfield specified. May also be assigned to. BITS must be a
-power of two from 1 to 32.
+Treats the string in EXPR as a vector of unsigned integers, and
+returns the value of the bitfield specified by OFFSET. BITS specifies
+the number of bits that are reserved for each entry in the bit
+vector. This must be a power of two from 1 to 32. vec() may also be
+assigned to, in which case parens are needed to give the expression
+the correct precedence as in
+
+ vec($image, $max_x * $x + $y, 8) = 3;
Vectors created with vec() can also be manipulated with the logical
operators |, & and ^, which will assume a bit vector operation is