Hello,

this is much needed addition.  It will take me a bit to read fully due
to its length, but few preliminary comments follow.

> Constructs a timezone object with the corresponding fields.

Should probably say `a timestamp object'.

> TZPATH

Why TZPATH and not TZDIR?  There might be a good reason for that, but it
is a shame the library will not work out of the box on GNU Guix (and
other non-FHS systems), so it would be nice to document the rationale.

> It is an error if time-delta is has hours, minutes, or seconds
> components.

I suspect there is a typo in the `is has'.

> strftime, strptime

Equivalents of these C functions are not present, but they are useful.
Is this omission intentional?

> The calculation is performed according to Annex D of the ISO
> 8601-2:2019 specification.

I find it bit unfortunate to reference non-free documents.  It makes it
impossible to implement the SRFI without buying the ISO document.  Maybe
it would be better to describe the rules directly in the SRFI?

I might have more questions later, once I have some time to do more
reading (both on the topic and of the SRFI specifically).

Have a nice day,
Tomas

--
There are only two hard things in Computer Science:
cache invalidation, naming things and off-by-one errors.