error in parsing xml

[senthil]

hi,
i tried to parse my xml in nsgmls(sp 1.3.4) in DOS mode, my errors are as follows

1. nsgmls:../pubtext/phflex3.5.8.dtd:1865:86:E: content model is ambiguous: when no tokens have been matched, both the 1st and 2nd occurrences of "OBJECT.REF" are possible
2. nsgmls:../pubtext/phflex3.5.8.dtd:1944:168:E: content model is ambiguous: when no tokens have been matched, both the 1st and 2nd occurrences of "LIBRARY" are possible

 how can i rectify these types of errors kindly let now,

Thanks and Regards
Senthil Kumar