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 # Expressions

 Last update: 16.10.2025 

Expressions are used to gather named entities needed for various operations.

The special characters used are `*`, `!`, and spaces or commas. These characters can be used within a string as follows:

- `abc\*` collects all required entities with a name starting with abc.
- `\*abc` collects all required entities with a name ending with abc.
- `\*abc*` collects all required entities with a name containing abc.
- `!abc\*` collects all required entities with a name that is not starting with abc.
- `\*abc,\*xyz` `\*abc \*xyz` collects all required entities with a name ending with abc or xyz. A comma or a space represents `OR`.

The following example uses expressions in the [`ScopeDefinition`](../api/_autosummary/ansys.meshing.prime.ScopeDefinition.md#ansys.meshing.prime.ScopeDefinition)class. The [`part_expression`](../api/_autosummary/ansys.meshing.prime.ScopeDefinition.part_expression.md#ansys.meshing.prime.ScopeDefinition.part_expression) parameter is used to gather part entities to define a scope. You can provide the exact part name or use expressions for more complex entity collections.

```pycon
>>> part = model.parts[0]
>>> # First part in model
>>> scope = prime.ScopeDefinition(model=model, part_expression=part.name)

>>> # All parts except solid
>>> scope = prime.ScopeDefinition(model=model, part_expression="* !solid")

```