> ## Documentation Index
> Fetch the complete documentation index at: https://axiom.co/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Type funtions

> This section explains how to use type functions in APL.

The table summarizes the type functions available in APL.

| Function                                                  | Description                                                                              |
| --------------------------------------------------------- | ---------------------------------------------------------------------------------------- |
| [iscc](/apl/scalar-functions/type-functions/iscc)         | Checks whether a value is a valid credit card (CC) number.                               |
| [isimei](/apl/scalar-functions/type-functions/isimei)     | Checks whether a value is a valid International Mobile Equipment Identity (IMEI) number. |
| [ismap](/apl/scalar-functions/type-functions/ismap)       | Checks whether a value is of the `dynamic` type and represents a mapping.                |
| [isreal](/apl/scalar-functions/type-functions/isreal)     | Checks whether a value is a real number.                                                 |
| [isstring](/apl/scalar-functions/type-functions/isstring) | Checks whether a value is a string.                                                      |
| [isutf8](/apl/scalar-functions/type-functions/isutf8)     | Checks whether a value is a valid UTF-8 encoded sequence.                                |