[R] How to interpret some diagnostic output

I do not know if I have a problem or not. The R script at the end of this email seems to run properly and a I get a boxplot that looks proper but I get the long string of messages during execution of the script looking like: ... The following object(s) are masked from dat ( position 8 ) :

[R] DBI fetch argument ellipses?

Sorry, this is an R newbie question: I have managed to sucessfully do some of the basic access of a MySQL data base with R but I have a question about the 'fetch' function. The documentation refers to fetch(res, n, ...) but never fully describes the ellipses (...) nor provides examples of what