LM3S5D91 Datasheet, PDF (1020/1340 Pages) Texas Instruments – Stellaris® LM3S5D91 Microcontroller

Universal Serial Bus (USB) Controller
Bit/Field
2:0
Name
reserved
Type
RO
Reset
0x0
Description
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
1020
Texas Instruments-Production Data
January 22, 2012