There is a bug in Symbian Word for 7710 which has been verified both on the device and on the WINS emulator.
When saving a file in the native format, the segment of style codes between the style definition segment and the text segment is left out.
One serious direct effect of this bug is that Word files saved from the 7710 cannot be read by the 9500, 9300 and 9210. Since Symbian Word files saved on all the aforementioned devices have the same header UIDs, they will be recognised. Attempting to open a file created in the 7710 on a 9500, 9300 or 9210 will leave without any error message.
(Note: in 9500, 9300 and 7710, Symbian Word is confusingly called 'Documents')
However, correctly formatted Symbian Word files saved in a 9500, 9300 and 9210 can be read by the 7710.
Due to the missing codes, formatting Word files with Styles on the 7710 would show serious defects, but I have not been able to verify at this point exactly which.
I can send heximages to show what I mean. Please contact me at firstname.lastname@example.org