For large scenes/models, the normal .usd binary/compressed version is often used for efficiency reasons (and proper round-tripping of float values for xforms, etc), but you can convert between the two with the 'usdcat' util and the python/c++ apis for debugging.
Why do so many (all?) textual data serialization formats represent floats in base-10 scientific notation, anyway?
If we wanted floats that are 1. human-editable but 2. bijective with IEEE754, wouldn't floating-point hexadecimal (and "e" notation representing a base-2 exponent) be a better idea?
I mean, depends on the human. Most don't know hexadecimal, but know what 3.14 means.
The real issue is why do so many float parsers and printers fail to do exact round tripping? Designing a good algorithm for this was a bit difficult, but these days this is a solved problem.
That combined with almost zero package management for retrieving things that were solved decades ago means we keep coming into this issue, partially because of the mindset of C programmers.
but then you loose the human readability / "understand-ability at a glance" advantage, so it sort of depends what the use-case is...
So 5e3 is a float; 3/8 is a float; and 5e3+3/8 is a float. Each cleanly and exactly representing particular IEEE754 values, while also being readable as a base-10 polynomials.
Maybe fractions of arithmetically-specified powers of two could also be allowed, for really big denominators. 3/2**26, for example.
The conversions are not even that hard ... unless you want to deal with arbitrary (and arbitrarily long) decimal representations and not just those that arise from IEEE numbers. Essentially the only choice to make is whether the conversion to decimal will emit all the digits all the time (simpler) or the shortest number of digits that will round to the requested IEEE float when read back (less liable to be mocked in webcomics[1]).
Of course, using hex floats is much simpler than even the simplest implementation of the above; I just want to point out that IEEE floats are perfectly roundtrippable through decimal.
