Format of short repeats varies in strange manner

[Peter Gentry]

This is my first venture into LilyPond so please bear with me if the question highlights my ignorance rather than a problem with the code.

 I have attached a short snippet to illustrate my problem concerning short repeats.

The vertical placing of the mark(s) between two repeated notes varies in a way I cannot understand and is different from the manual example which is also included.

(I have also found it impossible to place the trill mark higher up away from the stave.)

In general I am hamstrung by my lack of a programmers manual that species the syntax of all the various different engraver objects – is such a thing available anywhere?

 

regards
Peter Gentry

 

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