ARM VERSION 1.2 - Manual (Page 171)

ARM Instruction Reference
ARM DUI 0068B Copyright © 2000, 2001 ARM Limited. All rights reserved. 4-61
Architectures
This instruction is available in all T variants of ARM architecture v5 and above.
Examples
BLX r2
BLXNE r0
BLX thumbsub
Incorrect example
BLXMI thumbsub ; BLX label cannot be conditional