A release update pack increments the third section of the release number, for example to 12.1.1 or 12.1.2, and consists of a cumulative aggregation of product family release update packs created across Oracle E-Business Suite since the initial (base) release.
Oracle E-Business Suite Release 12 includes numerous products, all have abbreviated names or two or more usually three letters. These short names are used in special patch names. Common examples include Applications Technology (ATG), Business Intelligence (BIS), Financials (FIN), Human Resources (HR), and Supply Chain Management (SCM).
A product family release update pack is an aggregation of patches created for a specific product family after the initial release, and designated by the release number followed by the product short name and a letter. For example, in 'R12.ATG_PF.A.DELTA.6', '12' is the major release number, 'ATG_PF.A' means 'Applications Technology Product Family pack A', and 'delta.6' means this is the sixth rollup patch on top of Applications Technology Product Family pack
A codelevel is essentially a rollup patch with a name that looks like a version number. Higher codelevels include more changes, and include all fixes from lower codelevels. For example, R12.AD.A was the initial release of AD in Release 12. R12.AD.A.1 was a higher codelevel, which included all code in R12.AD.A plus additional fixes; R12.AD.A.2 was a higher codelevel again, which included all code in R12.AD.A.1, plus further fixes.
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