From the 2.0.10 -> 11 patch:
+ /*
+
+ This code has been modified from its original form by psoTFX @ phpbb.com
+ Changes introduce the back-ported phpBB 2.2 visual confirmation code.
+
+ NOTE: Anyone using the modified code contained within this script
MUST include
+ a relevant message such as this in usercp_register.php ... failure to
do so
+ will affect a breach of Section 2a of the GPL and our copyright
+
+ png visual confirmation system : (c) phpBB Group, 2003 : All Rights
Reserved
+
+ */
+
And GPL (2
a) You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
Ummm...., er, what?
[note: I haven't contacted the phpBB maintainer or upstream. ]