The one time I've seen this particular problem in action this was exactly the case.
Additionally the XML and question was all precisely to the byte level the same until you hit the giant (100s of Megs) based 64 blob that was the content. The parser stripped X number of bytes from the start of the file, and from the end, and de-base-64ed the center - which if I recall it then sent off to another parser as the content was in some old but standard record format from the 80s.
Anyhow - I'd say using XML in this case was the abuse, not the substring. But we were in no position to get the vendor to change their data format so...
Additionally the XML and question was all precisely to the byte level the same until you hit the giant (100s of Megs) based 64 blob that was the content. The parser stripped X number of bytes from the start of the file, and from the end, and de-base-64ed the center - which if I recall it then sent off to another parser as the content was in some old but standard record format from the 80s.
Anyhow - I'd say using XML in this case was the abuse, not the substring. But we were in no position to get the vendor to change their data format so...