[TYPO3-ttnews] genericmarker and wrap category selection

[berfh at gmx.de]

Dear all, 

I insert into the "tt_news" an additional select field (Author_Names) which is filled from the tt_news_cat. Multiple selection should be possible. The output of this field will displayed correct in the frontend with the marker ###GENERIC_AUTHOR_NAMES###. However, each author should be separated with a comma - except for the last author, there shouldn’t be a comma displayed. 
It should looks like: Author 1, Author 2, Author ... Author 5 
My current approach provides all the entries separated by comma, but unfortunately also a comma after the last author. How can the above example be realized (no comma after the last author)? 

My previous approach was: 
author_names = RECORDS 
author_names {
tables = tt_news_cat 
source.data = field: Author_Names 
conf.tt_news_cat = TEXT 
conf.tt_news_cat.field = title
conf.tt_news_cat.wrap = |,  
} 

Many thanks for your help,
Gunther