[neilv]

This "like standard protocol/format X, but strangely invalid" is a thing I've seen many times.

I speculate that one of the ways this happens is that someone decides or is told to use format Foo. Then they and possible collaborators implement both the writer and the reader for their idea of Foo from scratch, never testing with an off-the-shelf standard parser.

You'd think that doing XML like this is unlikely, given how easily available correct and validating parsers have been. But I've nevertheless seen this with XML too. I speculate that sometimes the programmer is on a platform that doesn't have an easily available off-the-shelf parser/writer, or they simply don't know about it.

I've also seen a variation of this, in half-butted "integrations", like to have a sales check-off feature of "we can generate X". These are sometimes tested only lightly, and sometimes not at all (such as when they don't have access to the tool that uses that format, and they were just working from poor documentation or an example). It's a thing.

[lpapez]

> I speculate that sometimes the programmer is on a platform that doesn't have an easily available off-the-shelf parser/writer, or they simply don't know about it.

I bet this sounds surreal to people visiting this site, but there are really corporations out there running on software written by people who never heard of XML. Another example is a "database" implementation I have seen in a multi-billion dollar company which relied on a hierarchy of directories containing JSON files mimicking tables and rows inside a relational DB.

The particular product in question had tens of millions of dollars yearly revenue.

[tonyedgecombe]

>You'd think that doing XML like this is unlikely, given how easily available correct and validating parsers have been. But I've nevertheless seen this with XML too.

Guilty.

Although in my defence it was during the early days of XML and the platform options had their own problems.