### 15.4.6 Data Types

Here is the command for data types:

`@deftp category name attributes…`

  The `@deftp` command is the generic definition command for data types. The command is written at the beginning of a line and is followed on the same line by the category, by the name of the type (which is a word like `int` or `float`), and then by names of attributes of objects of that type. Thus, you could use this command for describing `int` or `float`, in which case you could use `data type` as the category. (A data type is a category of certain objects for purposes of deciding which operations can be performed on them.)

  In Lisp, for example, pair names a particular data type, and an object of that type has two slots called the CAR and the CDR. Here is how you would write the first line of a definition of `pair`.

      @deftp {Data type} pair car cdr
      …
      @end deftp

  The template is:

      @deftp category name-of-type attributes…
      body-of-definition
      @end deftp

  `@deftp` creates an entry in the index of data types.