Some pieces of software seem to jump version numbers with every minor revision, while others seem to never change.
Yet, although the product receives updates, it will not get a new number in the near future because HP wants to communicate that applications will continue to run smoothly on any 11-series release, even on the newest versions.
"If we move to a version 12, that would be a flag that something has changed and that users and developers need to recode or re-compile," Brian Cox, worldwide director of BCS software marketing, HP told InternetNews.com. "As it is, you can take any application from the very first HP-UX version 11 up to the recent HP-UX 11i Update 3 and it will run."
"Our customers and partners hold compatibility of their applications to be at such regard that we don't want to violate that trust," Cox said.
Though HP has shied away from moving its major version numbers forward, it hasn't stopped from putting out major releases.
The most recent major update of HP-UX 11i was Update 3, which was released nearly a year ago in February 2007.
HP's updates also have lengthy supported lifespans, with Update 3 set to be supported by HP until 2017.
Cox explained that with HP-UX 11i version 1 and Update 2, the emphasis was on scalability. With Update 3, HP started building out the foundation for virtualization.
In Update 4, which isn't expected until at least 2010, the plan is to provide better manageability of virtualized environments and even higher uptime levels than currently possible, Cox said.
HP has also produced interim enhancement releases between major updates. The interim releases, which come out every six months, provide bug fixes and other small tweaks.
Following the Update 3 release in February 2007, HP issued a interim update in fall, codenamed "Vitality," Cox said.
"Then, coming out this spring, we have another enhancement codenamed 'Versatility,' and then six months after that, the update is codenamed 'Vibrancy,'" Cox said. "We'll continue to march that forward until version 4, which will be a major new release."
HP's release schedule has entailed some massive changes for the operating system. With the HP-UX 11i release, for example, HP embraced the new Unix03 standard, which aims to provide application portability across Unix03-certified operating systems.
To date, IBM's AIX 5L V5.3, Sun Solaris 10 as well as Apple's OS X version 10.5 (aka "Leopard") have been certified to be Unix03-compliant.
HP's joining the ranks marked a significant development not just for HP-UX for which Unix03 was just the latest in a long wave of Unix certification efforts over the years but for the industry.
"Standardization for the APIs makes it easier for software developers to write and port code, and it lowers their cost of maintenance," Cox said. "It's in classic contrast with the mainframes of the past where portability didn't exist."
This article was originally published on InternetNews.com.