[MASSEMBLY-1032] should be able to create ustar archives (i.e. non-posix/non-GNU)

**[Benjamin Marwell](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=mampf86)** opened **[MASSEMBLY-1032](https://issues.apache.org/jira/browse/MASSEMBLY-1032?redirect=false)** and commented

Currently, the tar option will always create POSIX archives or GNU archives.
However, not all implementations of tar can handle this: https://savannah.gnu.org/support/?109437

AIX 7.2 will unpack Directories named PaxHeaders.X, not sure about what happens with GNU tar archives.

However, given that ustar is more universal until AIX 7.3.1 arrives, it would be a reasonable option to support ustar as well. Even after that AIX release, it might be a reasonable choice for other Unix-like systems, as the posix standard has not been adopted widely.

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**Issue Links:**
- [COMPRESS-683](https://issues.apache.org/jira/browse/COMPRESS-683) support ustar format
(_**"is blocked by"**_)

Start at the Maven Assembly Plugin's tar option handling and review the linked COMPRESS-683 issue, which blocks this work. Determine how a ustar format option can be supported alongside the existing POSIX and GNU formats; done means the plugin can create ustar archives suitable for systems such as AIX.

Written by the indexing model from the issue text.