This is METAFONT, Version 2.718281 (TeX Live 2012/Debian) (base=mf 2012.11.2)  19 NOV 2012 12:39
**italig.mf
(italig.mf
>> -x_height#+asc_height#
>> slant
! Not implemented: (unknown numeric)*(unknown numeric).
<to be read again> 
                   +
l.8 itc=(asc_height#-x_height#)*slant+
                                      .75u#;
? x