System.ComponentModel.MaskedTextProvider can treat two categories of characters, spaces and prompt characters, in a special manner. Normally, each input character will be tested against the mask and either accepted or rejected. Setting the MaskedTextProvider.ResetOnSpace property to true will result in the current mask character position being cleared and the current position being advanced to the next editable character.

MaskedTextProvider.ResetOnSpace is useful when assigning text that was saved excluding the prompt, where the prompt is replaced with a space. Before restoring such a string, setting MaskedTextProvider.ResetOnSpace to true will reset the prompt characters at the positions occupied by spaces in the input string.