You can create namespaces in the Namespace Editor as well as when you reference or import a file into your scene. When you create a namespace during file referencing or importing, the file name is used as the namespace by default.
After you create a namespace you can edit it using the Namespace Editor. See Edit namespaces.
To create a namespace using the Namespace Editor
The Namespace Editor appears.
Maya creates a new namespace.
The Rename Namespace window appears.
When importing a file, you can create the namespace used by the referenced and imported objects.
To create a namespace during import
The Import Options window appears.
In the case where duplicate namespaces occur, the namespaces are merged and duplicate object names are incrementally suffixed with a number. Use this option to avoid an accumulation of new namespaces each time your referenced or imported objects have the same namespace.
A File Browser appears.
You can edit namespaces using the Namespace Editor. For more information see Namespace Editor overview.