Infrastructure software that is the building blocks or base platform for domain applications software or used by application developers. Examples include:
Quasi-SystemsSoftware are tools that may cater to a domain or specific shop, but are more "core" to the applications. For example, an in-house GUI library that creates a customized view or version of a more general GUI library that fits shop conventions and needs better. Such tools are pre-digesting a vendor or "general purpose" GUI library to hide features not typically used by the shop and streamline for patterns heavily used by the shop.