-BUFFER is the buffer to evaluate (nil means use current buffer).
-PRINTFLAG controls printing of output:
- A value of nil means discard it; anything else is stream for print.
+BUFFER is the buffer to evaluate (nil means use current buffer),
+ or a name of a buffer (a string).
+PRINTFLAG controls printing of output by any output functions in the
+ evaluated code, such as `print', `princ', and `prin1':
+ a value of nil means discard it; anything else is the stream to print to.
+ See Info node `(elisp)Output Streams' for details on streams.