There are currently (2019) two versions of WARC: 1.0 and 1.1, formally ISO 28500:2007 and ISO 28500:2017, respectively.

Version 1.0 formally specified that URLs in the WARC-Target-URI field should be surrounded in angle brackets, but erroneously did not show this in examples. Implementations largely followed the examples, with the notable exception of Wget, a popular WARC-producing program, which, since February 2016, has used the angle brackets, with the result of breaking much of the software that reads its output. The angle brackets were eliminated altogether in WARC 1.1.