...and 1 year later ;-)

Your question is pretty tricky because SK elements are (despite being structured elements) created by airlines themselves iaw. their needs. SK elements kan be very different, e.g.

• pax and flight segment association mandatory, conditional, optional or not possible

• action/status code or not

• freetext be mandatory/optional/not allowed

• structured text required, i.e. instead of free text, the system will validate that your text matches a given pattern

• ...and more

So it's tricky (if not impossible) to give you an XML example unless we know something about the element type itself (the 4 letter code, in your case for LH).

With regards to the XML you have included, I think it looks pretty straight forward. The structure generally follows that of an SSR element, and you have e.g. pax referencing correct. (Flight segment referencing would be ST, as you're probably used to from SSR element processing.) I'm questionning whether you should send HK action code; This is not common (and it is in reality a status code, not an action). I don't think you should probably send NN with the request, and you'll get the status code back with the PNRACC response.