## `Type::Unknown` -- type for testing variables

#### Introduction

`Type::Unknown` represents identifiers and indexed identifiers.

#### Call(s)

`testtype(obj,` Type::Unknown)

#### Parameters

`obj` | - | any MuPAD object

#### Returns

see `testtype`

#### Related Functions

`testtype`, `indets`

#### Details

- The call `testtype(obj,` Type::Unknown) checks, whether `obj` is an identifier or an indexed identifier with an integer index. If it is, the call returns `TRUE`, otherwise `FALSE`.
- An identifier has the domain type `DOM_IDENT`. An indexed identifier is an expression with type `_index` and two operands, the first of which is an identifier and the second one is an integer. A local variable is not of type `Type::Unknown`.
- This type does not represent a property.

#### Example 1

`Type::Unknown` accepts identifiers:

    >> testtype(x, Type::Unknown)

                                       TRUE

`x[0]` is an indexed identifier accepted by `Type::Unknown`:

    >> testtype(x[0], Type::Unknown)

                                       TRUE

The index must be an integer:

    >> testtype(x[-1], Type::Unknown),
       testtype(x[1.0], Type::Unknown)

                                    TRUE, FALSE

#### Changes

- no changes

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