The IAB's own VAST sample tags pass XSD validation, and two of them still break the spec
If you build a video player, an ad server, or anything that touches VAST, the IAB Tech Lab VAST_Samples repo is probably where you got your test fixtures. I ran every file in it through two checks: xmllint against the official IAB XSD for each file's declared version. vastlint , an open-source linter with 235 rules taken from the XSDs and from the normative text of the spec (the RFC 2119 "must"…
The IAB Tech Lab's VAST_Samples repository contains test fixtures for video ad tags, and the author ran all the files through two checks: xmllint against the official IAB XSD and vastlint, an open-source linter with 235 rules. Out of 75 files, 4 had spec errors, 72 had warnings, and 2 files passed the XSD but broke the VAST 4.1 spec text.
The two files that passed the XSD but violated the spec are VAST 4.1 and VAST 4.2 samples. The issue lies in the Optional attributes Vendor and APIFramework, which are required according to the specification text. xmllint validates the files because it only checks the structure, whereas vastlint also checks the prose-based rules, thus identifying the issues.
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