Command Structure and Syntax

Valid commands to the tracking programs consist of a keyword which is sometimes followed by a number of other alphanumeric parameters. For example, the command line
RA 191936.1
causes a new Right Ascension, 19$^h$19$^m$36.1$^s$, to be accepted by the computer. (It is understood that a carriage return is to be entered after the typing of a command line.) Before the command is entered, you may backspace and write over portions of your command as you would any line of entry to a computer.

However, no inline editing is permitted, so backspacing to correct an error requires retyping of the rest of the line.

The following rules of syntax apply for valid keywords and their arguments:

1. Any convenient number of commands may be strung together on the same line, as in the command:
   RA 191936.2 DEC 214712 NAME PSR1919+21.
   which would enter the Right Ascension, Declination, and Name of the source PSR1919+21 into the global common and cause these coordinates to be tracked if the programs are running in POINT mode.

2. Only the first four letters of a dictionary keyword are significant, with the first blank space defining the end of a keyword or argument. Thus the following are all equivalent entries:
   CATALOG CATAMARAN CATALOGUE CATAPAULT
   and all would be interpreted as the CATALOG keyword. On the other hand, the three letter string CAT is not defined and would not be recognized.
3. Numerical parameters are freeform: leading zeros and signs and a trailing decimal point are optional. Embedded blanks are not permitted because the first blank defines the end of the parameter. Right ascensions and declinations are entered in the form hhmmss.s and ddmmss.s with no embedded blanks.

The program responds to illegal commands by ringing the command terminal's bell; any part of the command following the error is not processed, and the program waits for another command line to be entered. When command processing stops because of an entry error, a brief message is displayed on line 23 of the current screen as an indicator of the nature of the error. The messages include:

LOGIC ERR -

command makes no sense

RANGE ERR -

numeric value out of allowed range

ARG MIS ERR -

an argument has been left off

ARG TYP ERR -

an argument was a word when it should have been a number, or vice versa

ARG BAD ERR -

for word arguments, the word is not a legal choice

SYNTAX ERR -

catch-all for miscellaneous errors

CMND ERR -

undefined command

LOCKOUT ERR -

a remote observer has attempted to enter a command which is illegal unless the command REMUNLOCK has been entered by an observer at the site.