### C PONGO and the MONGO Graphics Package

PONGO has been designed to have broadly the same command interface as that offered by the MONGO6 graphics package. A number of aliases (ICL DEFSTRING definitions) have been set up for certain commands so that PONGO will do more or less what is expected for the equivalent MONGO command, but there are some substantial differences. It might well be possible to do a better job of imitating MONGO using ICL procedures; however, the aim is not to imitate the precise behaviour of MONGO, but for existing users of MONGO to be met with a package that is not totally unfamiliar to them when they begin using PONGO. Ultimately, PONGO offers substantially more than MONGO, both by its flexibility and by what it can do.

 Command Behavioural differences BOX The optional arguments are different in the two cases. CONNECT DATA DRAW ERASE ERRORBAR The way in which the errors are plotted is different. LTYPE The actual styles produced are different. EXPAND In PONGO this will also alter sizes of tick-marks. LWEIGHT PCOLUMN The symbol numbers in the file refer to the standard PGPLOT marker symbols. PEN POINTS PONGO has additional optional arguments. XCOLUMN In PONGO a symbolic name can be used optionally for the column description. XLINEAR In PONGO no arguments can be given. The array is always filled in an increasing integer sequence from one. It is possible to perform any desired manipulation on the values in the column using the CCMATH command. XLOGARITHM YCOLUMN In PONGO a symbolic name can be used optionally for the column description. YLINEAR In PONGO no arguments can be given. The array is always filled in an increasing integer sequence from one (see the description of XLINEAR). YLOGARITHM

Table 2: Commands which have nearly the same effect in MONGO and PONGO

Having read the rest of this document it will have become clear that there are a substantial number of differences between MONGO and PONGO: perhaps most significantly, it is not possible to run a MONGO script file and expect it to work. The most important difference at the command level is that once XCOL etc. have been set up, the data must be input explicitly using the READF command, where MONGO would read the data in each time that a command that needs them is executed. Table 2 is a list of the commands that work as expected (with the above proviso) and Table 3 gives a list of the closest equivalents to MONGO commands.

 MONGO PONGO Behaviour AXIS BOXFRAME Most effects achievable by can be accomplished by altering the parameters of the BOXFRAME command. BADY READF Use the COND parameter to selectively read the file. ECOLUMN EXCOLUMN The errors for the X and Y directions are read separately in PONGO. EYCOLUMN The errors for the X and Y directions are read separately in PONGO. GRID BOXFRAME A grid can be drawn by using G in XOPT (not to be confused with PONGO command GRID). HARDCOPY HISTOGRAM PLOTHIST Use the command PLOTHIST B (note that the command PLOTHIST H will automatically bin unbinned data). LABEL WTEXT PONGO is more flexible. LINES READF Use the FROM and TO parameters. PTYPE POINTS PONGO is restricted to the standard PGPLOT symbols: although there are 32 of them, you cannot define your own as you can in MONGO. PUTLABEL WTEXT

Table 3: PONGO command equivalents for certain MONGO commands

6The MONGO package was once available at all Starlink nodes, at the time of writing this is no longer the case, so this reference, indeed this whole section, is now largely historical.