Do `Grapheme_Extend` characters only apply to `Grapheme_Base`?

[Mathias Bynens]

On 23 Apr 2014, at 22:16, Mathias Bynens <mathias at qiwi.be> wrote:

> Let’s say I’m writing a program that strips combining characters and grapheme extenders from an input string.
> 
> For combining marks, I’m looking for any non-combining marks (e.g. `a`) followed by one or more combining marks (e.g. `̃`), and then I remove everything but the non-combining mark (e.g. leaving only `a`). Is this a correct approach?
> 
> What should the approach be for grapheme extenders? Should the program only look for `Grapheme_Base` characters followed by `Grapheme_Extend` characters (which includes the code points in `Other_Grapheme_Extend`)?

The email subject should have been “Do `Grapheme_Extend` characters only apply to `Grapheme_Base`?” — sorry for the confusion.

Does anyone know the answer?