NAME
    iserror - test whether a value is an error value

SYNOPSIS
    iserror(x)

TYPES
    x		any

    return	zero or positive integer < 32768

DESCRIPTION
    If x is not an error value, zero is returned.
    If x is an error value, iserror(x) returns its error type.

EXAMPLE
    > a = error(99)
    print iserror(a), iserror(2 + a), iserror(2 + "a"), iserror(2 + 3)
    99 99 3 0

LIMITS
    none

LIBRARY
    none

SEE ALSO
    error, errorcodes,
    isassoc, isatty, isblk, isconfig, isdefined, iseven, isfile,
    ishash, isident, isint, islist, ismat, ismult, isnull, isnum, isobj,
    isobjtype, isodd, isprime, isrand, israndom, isreal, isrel,
    issimple, issq, isstr, istype