Epson S2R72V18 Technical Manual page 322

3. Register Details
When the amount of data set in D_DescSize_H,L has been sent or if a transaction other than an IN
transaction is performed, the descriptor reply function ends, the ReplyDescriptor bit is cleared to
"0," and the D_EP0IntStat register DescriptorCmp bit and D_EP0IntStat register IN_TranACK bit
are set to "1."
For further details, refer to the section that describes how functions are used.
EPSON
S2R72V18 Technical Manual (Rev.1.00) 305