sysname and longsysname Datatype

sysname and longsysname are user-defined datatypes used in the system tables.

sysname is defined as:
varchar(30) "NOT NULL"

longsysname is defined as:

varchar(255) "NOT NULL"

You can declare a column, parameter, or variable to be of type sysname or longsysname. Alternately, you can also create a user-defined datatype with a base type of sysname or longsysname.

You can then use this user-defined datatype to create columns.

Related concepts
User-Defined Datatypes