[R] foreign:::writeForeignSPSS vs. write.foreign(df, datafile, codefile, package='spss')

[Simon Kiss]

Hello:
I discovered recently that the function foreign:::writeForeignSPSS allows for variable names longer than 8 characters and has an additional argument varnames.  Neither of these capabilities exist with write.foreign. But according to the help file for write.foreign it seems that the latter actually somehow calls the former.  Am I reading this wrong? Can someone explain the difference between the two functions?
Thanks.
Yours, Simon Kiss