What's the 's' (the help doesn't say)? And how is this form of the function supposed to work? That syntax would seem indistinguishable from @B64ENCODE[inputfile,outputfile]. And the seemingly likely alternative, @b64endode[string] causes an error. Code: v:\> echo %@b64encode[string] TCC: (Sys) The parameter is incorrect. "%@b64encode[string]"