Most high end "enterprise" products (CRM, ERP) have entire weird development eco-systems embedded within the product - complete with their own languages, database access mechanisms etc.
What I actually find quite interesting about some of these products is the way they are architected to support multiple overlapping customizations from 3rd party vendors, customer specific customizations and the "core" of the application itself.
e.g. I've worked on an ERP project that had the base product, customizations within the product, very complex integrations with other systems and over ten 3rd party products that ran on the ERP systems own platform. That was fun... :-)
What I actually find quite interesting about some of these products is the way they are architected to support multiple overlapping customizations from 3rd party vendors, customer specific customizations and the "core" of the application itself.
e.g. I've worked on an ERP project that had the base product, customizations within the product, very complex integrations with other systems and over ten 3rd party products that ran on the ERP systems own platform. That was fun... :-)