Continuation lines for long lists of columns and expressions

Occasionally you might need to enter a long list of columns and expressions for display (catview option SETCMP) or a long expression for a selection (catview option SETSEL). In both these cases a continuation line mechanism is available which allows lists and expressions which are longer than a single input line to be entered. This option is only available in catview, not in xcatview. If you need to specify long lists of columns and expressions to be displayed, or a long expression defining a selection, then you must use catview. In practice this restriction is not too onerous because long lines usually arise when expressions are being used to compute a set of new columns, which is often done from the command line anyway.

In order to extend the list of columns and expressions to be displayed across several lines simply append an `@' character to the end of the line to be continued. The prompt:

CMPLIST - Columns to be listed>

will be repeated and the line can be continued. The details are as follows.

• An arbitrary number of continuation lines can be entered.

• A line which does not end in `@' is assumed to be the last.

• The `@' used to indicate continuation lines is quite separate from the `;' used to separate columns and expressions; ending a line in `@' does not allow a `;' to be omitted.

• The list can be split at any point: in the middle of names, expressions etc. (though the input is more easily read by eye if it is split at a natural break point such as the end of a column name).

Though this mechanism allows long lists and expressions to be entered, there are necessarily still limits on the length of the list of columns and expressions for display and on expressions defining selections, because they are represented within catview as Fortran 77 CHARACTER variables. In version 6.4 of CURSA these limits are:

List of columns and expressions for display:	1000 characters.
Expression defining a selection:	200 characters.