[metapost] paucity of i/o files

[Bzyl Wlodzimierz]

Taco asked

> You *can* close a file, by sending a string consisting solely of
> an ascii zero to it.
...
> I am not at all sure that this is documented, though. ;-)

Hans answered

| no

But, Hobby wrote

``Some recently-added features of the languages are documented only
  in a separate report.''

 Drawing Graphs with MetaPost, AT&T Bell Laboratories Computing
 Science Technical Report 164, 1992.
 (pdf available from: http://cm.bell-labs.com/who/hobby/mppubs.html)

 These new features include: image macro, readfrom, write
 operators, EOF, extracting information from pictures
 and some other stuff.

 What about moving the whole Appendix B ``New Languague Features''
 from the Technical Report 164 to the mpost user manual?

--Wlodek Bzyl