Reference Data Management Applications - both custom and purchased.
Originally involved with "master code" designs in the early 1990s on mainframe in Vsam and Adabas. Then in Oracle twice using PlSql once with Excel as data entry form and another using custom .Net front end. Somewhat related (but more pure MDM) was custom built customer hierarchy management using Oracle Express and Express Objects. Later in mid-2000s using Hyperion's MDM which came from Razza Solutions (now Oracle Data Relationship Manager). Currently using Microsoft's Master Data Management.
Never custom build when there are now so many products available which provide user interfaces and provide many services that are impractical to build on your own. Reference data management is very patterned in structure and with low volumes of data so fits well using pre-built vendor supplied (COTS) tools rather than build-your-own. I would not try to force fit a hierarchy management tool to just do RDM like we did with the Hyperion tool as it was actually far more difficult trying to make the tool do what we wanted it to than building it ourselves. It's only in the last decade that RDM has become recognized as a valued practice and thus tools are evolving to meet the need. Largest issue especially when building your own is supporting M:M and more complex boolean mapping rules and providing governance workflow. My approach now is first identify what tool will meet needs and has low learning curve with easy sustainability.