Each of these $x = 123; print UNIVERSAL::isa($x, "UNIVERSAL") ? 'T' : 'F'; $x = 'fish'; print UNIVERSAL::isa($x, "UNIVERSAL") ? 'T' : 'F'; $x = undef; print UNIVERSAL::isa($x, "Stuff" ) ? 'T' : 'F'; do print 'F', as expected. But this $x = undef; print UNIVERSAL::isa($x, "UNIVERSAL") ? 'T' : 'F'; prints 'T'. UNIVERSAL::isa ( VAL, TYPE ) isa returns true if the first argument is a reference and either of the following statements is true. VAL is a blessed reference and is blessed into package TYPE or inherits from package TYPE VAL is a reference to a TYPE of perl variable (er 'HASH') I take the "if" to mean "if and only if", so UNIVERSAL::isa(undef, anything) should return false. Also, I suggest s/er/e.g./, and s/perl/Perl/ in the text there. -- Sean M. Burke sburke@netadventure.net http://www.netadventure.net/~sburke/Thread Next