My own experience is that (unix) timestamps are much less error-prone than textual representations like ISO 8601 and such. A field like `update_time_seconds` is

My own experience is that (unix) timestamps are much less error-prone than textual representations like ISO 8601 and such. A field like `update_time_seconds` is clear and easy to convert into any representation. This is what the Google API Improvement Proposals recommends in most cases, though civil timestamps are also described. https://google.aip.dev/142 https://google.aip.dev/142 Of course, when preparing queries against the API, you may need a helper to build valid timestamps. But this is mostly relevant to the discovery phase which isn't automated. And textual dates also have drawbacks, for instance the need to encode it when used a an URL parameter.