2.What is a root segment?
A segment that lies at the top of the hierarchy is called the root segment. It is the only segment through which all dependent segments are accessed.
3.What are twin segments?
Two or more segment occurrences of a particular segment type under a single parent segment occurrence are called twin segments.
4.Define segment occurrence.
A segment occurrence is an individual segment of a particular type containing user data.
5.What is a database record?
Each occurrence of the root segment plus all its subordinate segment occurrences make up for one database record.
6.What is the limitation on the number of levels in a DL/I database?
We can have 15 levels in a DL/I database.
7.How many segment types can you have in a DL/I database?
A DL/I database can have 255 segment types.
8.What are the control blocks in IMS?
There are two control blocks: the Database Descriptor (DBD) and Program Specification Block (PSB).
9.What are common DLI functions?
The common functions are GU, GN, GNP, GHU, GHN, REPL, ISRT, and DLET.
10.What are the command codes and their purposes?
Command codes extend the function of an SSA call. They simplify programming and improve performance.