ARM VERSION 1.2 - Manual (Page 95)

Assembler Reference
ARM DUI 0068B Copyright © 2000, 2001 ARM Limited. All rights reserved. 3-17
If routname is specified in either a label or a reference to a label, the assembler checks it
against the name of the nearest preceding ROUT directive. If it does not match, the
assembler generates an error message and the assembly fails.