There is description in Reference manual.
184.108.40.206 Parallel interface data synchronizer and data oriented interface
The data accumulated in the DI's input buffer will be sent to the display according to the
DI's internal events. Each event is generated by a counter. A tag is attached to each data
by the DC's microcode using the SYNC field in the DC's microcode. The tag selects the
event that the data will be synced to.
1. What is the tag that attached by DC's microcode? Does it us internal only in DI?
2. How does the tag attach? Does it attach automatically in DC?