Specialist vs Senior position

[siber]

Hi All,

First of all, I want to thank all the people who contribute to this topic. It is really very helpful.

I'm just collecting all the stuff for HSMP app. now. After extensive reading I have quite clear idea about all but the one point:

What are the distinctive features of a "specialist" position as opposite to senior one?

I had been working as an IT specialist, as many here. I can't associate any "seniority" with that my job, but i was definitely a "specialist"!! (IMHO:))

"HSMP Bible" says
-- cut one --- p.14
" A specialist position is normally envisaged to be one that may not have any particular managerial role but requires a very high level of technical or artistic expertise."

--- cut two --- p.18
"A position recognised as specialised within the individual’s field of employment.
Work experience gained in jobs that normally require specialist skills or in shortage
occupations does not in itself count as specialist level work experience. For
example, a dentist would have to demonstrate specialised expert knowledge of a
particular area within the field of dentistry in order to score points for specialist
level work experience."

sorry for extensive citation, but that is all availiable info!!!

My question is:

How "a dentist" can demonstrate his "specialised expert knowledge"?

Could you provide (successful) examples of evidence? Examples of Statements in an employer letter that support this would be even more helpful.