---
title: "Time and identifiers"
description: "Normalize timestamps and explain the structure encoded in common identifiers."
---

> Documentation Index
> Fetch the complete documentation index at: https://help.serialize.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Time and identifiers

## Learning objectives

- Identify the epoch and unit behind a timestamp
- Convert batches without losing item boundaries
- Explain UUID version and variant fields
- Translate symbolic UNIX permissions
- Parse URI and IPv6 fields rather than treating them as opaque strings

## Timestamp labs

1. Install [Convert a time zone](/recipes/convert-timezone/) and identify the source format, source zone, target zone, and output format.
2. Install [Convert a list of UNIX timestamps](/recipes/convert-unix-timestamps/) and explain why Fork is placed first.
3. Install [Convert Windows FILETIME](/recipes/identifiers-time/windows-filetime/) and compare the Windows and UNIX epochs.

## Identifier labs

- [Analyse a UUID](/recipes/identifiers-time/analyse-uuid/)
- [Parse UNIX file permissions](/recipes/identifiers-time/parse-unix-permissions/)
- [Parse a URI](/recipes/identifiers-time/parse-uri/)
- [Inspect a Teredo IPv6 address](/recipes/inspect-teredo-ipv6/)

For each result, distinguish values directly encoded in the identifier from interpretations added by the parser.

## Assignment

Build a small synthetic timeline containing a UNIX timestamp, a Windows FILETIME value, and a human date with an explicit time zone. Convert them to a common UTC representation and record every unit and epoch assumption.

Source: https://help.serialize.dev/courses/time-and-identifiers/index.mdx