Hello Martin,
Thank you for contacting me.
About the MaskType property - a mask type defines what type of mask would be used in the masked box: DateTime, Standard, Numeric.
Documentation about RadMaskEditBox could be found in Editors/RadMaskedTextBox/. This is the only documentation available about this control at the moment, but expect an update with the next release.
If you have more questions please write me back.
Sincerely yours,
Boyko Markov
the Telerik team
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