[racingmars]

"Documents must be utf-8 and should have a byte order mark."

No. If you're using UTF-8 (which is a good choice), the use of a BOM should be discouraged. Given that the format specification says documents MUST be UTF-8, there is no need to enable detection of UTF-8 content with the UTF-8 BOM. And, of course, the original purpose of the BOM (detecting big- or little-endian encoding) is unnecessary in UTF-8.

The Unicode standard, section 2.6, says, "Use of a BOM is neither required nor recommended for UTF-8".

While it is allowed, if you're making a new spec for a new data format, you shouldn't recommend the use of a BOM in UTF-8.

[GeneThomas]

There exists a charset that is more efficient than UTF-8.

[GeneThomas]

I am futureproofing.

[slater]

Which is…?