The c-tree File Handler is a record-oriented file manager. However, to support intelligent key value operations, and to support higher level systems applications such as report generation, user interfaces, and ODBC, c-tree provides support for individual field definitions.
The definition of each field comprising a record can be stored in the data file itself if the data file has not disabled RESOURCE support. The d-tree component of the FairCom ToolBox automatically stores the record schema in the data file, or you can do it yourself by calling PutDODA(). The advantage of storing the schema is that applications can use this information without any outside information. Further, c-tree can use field numbers to specify key segments if the schema is stored in the file, enabling new and more flexible key segment definitions.
This section discusses the structure of the Record Schema Resource, the DODA, how it can be used to define Key Segments, and how you can create this resource via low-level c‑tree function calls.