Conditionally-Present Fields - Conditionally-Present Fields - 2026.1 English - UG1864

When a varray.axis configuration is attached to an array, the following sideband fields are present by default (controlled by their enable flags):

Field	Default	Python Type	MATLAB Type	Enabled When	Description
tlast	False	bool	logical	enable_tlast=True	Last transfer indicator. Marks the final beat of a packet.
tkeep	All 1s	uint64	uint64	enable_tkeep=True	Byte-level keep mask. Indicates which bytes carry valid data.
tstrb	All 1s	uint64	uint64	enable_tstrb=True	Byte-level strobe mask. Distinguishes data bytes from position bytes.

The all-ones default for tkeep and tstrb is based on the payload byte width. For example, 32-bit payloads default to 0xF and 16-bit payloads default to 0x3. Payloads wider than 64 bytes are rejected because the keep and strobe masks are represented as 64-bit values.