Namespace Summary (The GNU Awk User’s Guide)

Standard awk provides a single namespace for all global identifiers (scalars, arrays, and functions). This is limiting when one wants to develop libraries of reusable functions or function suites.
gawk provides multiple namespaces by using qualified names: names consisting of a namespace name, a double colon, ::, and a component name. Namespace names might still possibly conflict, but this is true of any language providing namespaces, modules, or packages.
The default namespace is awk. The rules for namespace and component names are provided in Namespace and Component Naming Rules. The rules are designed in such a way as to make namespace-aware code continue to look and work naturally while still providing the necessary power and flexibility.
Other parts of gawk have been extended as necessary to integrate namespaces smoothly with their operation. This applies most notably to the profiler / pretty-printer (see Profiling Your awk Programs) and to the extension facility (see Writing Extensions for gawk).
Overall, the namespace facility was designed and implemented such that backwards compatibility is paramount. Programs that don’t use namespaces should see absolutely no difference in behavior when run by a namespace-capable version of gawk.