Allow `@hand` in `<metamark/>`

[cthomasdta]

Dear all, I had in the back of my mind that @hand had gone global not so long ago, but it is not allowed as an attribute for <metamark/>.

I think @hand should be allowed in <metamark/>, just as <handShift/> is allowed there, but for those who prefer the more light-weight use of attributes inside container element instead of <handShift/>s.

What I want to do is indicate that the "graphic or written signal within a document […] the function of which is to determine how it should be read rather than forming part of the actual content of the document" (Def. <metamark/>) was written by another hand, which is referenced in the @hand-attribute as a value pointing to <handNote>. E.g.

<p hand="#ct">I was under the impression that  that `@hand` had 
gone global<metamark hand="#tei_Guru">🙈</metamark> not so long ago ...</p>

Or to give you a better, real-world example: A.v. Humboldt, the addressee of a letter, uses "[" and "]" or rather similar-looking signs to mark a span inside a text which is to be treated in some special manner (so it's neither <add> nor <note>):

<p><!-- […] --> vom August bis December über 5000 eingewandert
sind; – meist Irländer. <metamark hand="#addressee">[</metamark>Die Wahl des hiesigen Hamburger Consuls, 
Stakemann, zum preußischen Consul, <!-- […] --> 
Man spricht sogar von einer Remonstration dagegen.<metamark hand="#addressee">]</metamark> Wohl dürfen wir 
Euer Excellenz bitten<!-- […] --></p>

Please let me know if this should be discussed on the mailing list first, but IMO there's no discussion needed here, it's only consistent to allow @hand in <metamark/>.

[cthomasdta]

ah, never mind: I can solve it with <add>:

<p><!-- […] --> vom August bis December über 5000 eingewandert
sind; – meist Irländer. <add hand="#addressee"><metamark>[</metamark></add>Die Wahl des hiesigen Hamburger 
<!-- […] --> 
Man spricht sogar von einer Remonstration dagegen.<add hand="#addressee"><metamark>]</metamark></add>

[cthomasdta]

Closed, only to be re-opened should there be the need to actually apply @hand inside <metamark/>!