Hardening: version field

[mitsuhiko]

Today the specification says this about version:

File version (always the first entry in the object) and must be a positive integer.

It does not say that this is the source map spec version, but it implies this by showing the integer 3 everywhere for the source map version (v3). It could also be a running counter. It also is documented to come first in the file which in practice is not enforced and hard to actually enforce given that many languages only have unsorted hash maps.

Would it make sense to drop the ordering requirement and to mention that this is explicitly the version of the source map, and what meaning it has?

My recommendation would be:

1. it refers to the source map spec version
2. we define when this version is bumped, and what tools should assume (eg: does bumping means major version that is assumed incompatible?)

[mitsuhiko]

We agreed on requiring the value to be 3 and it was added to the spec. I consider this closed now.