XOR selected and saved

Command group Flag affected Reversible Execute on client Platform(s)
List lines YES NO NO All

Syntax

XOR selected and saved ([All lines]) {line-number (calculation)}

Options

All lines If specified, the command affects all the lines in the list

Description

This command performs a logical XOR of the Saved selection with the Current selection. To allow sophisticated manipulation of data via lists, a list can store two selection states for each line; the "Current" and the "Saved" selection. The Current and Saved selections have nothing to do with saving data on the disk; they are no more than labels for two sets of selections. The lists may be held in memory and never saved to disk: they will still have a Current and Saved selection state for each line but they will be lost if not saved. When a list is stored in the data file, both sets of selections are stored.

You can specify a particular line in the list by entering either a number or a calculation.

The XOR selected and saved command performs a logical XOR (exclusive OR) on the Saved and Current state and puts the result into the Current selection. Hence, if either of the Current and Saved states is selected, the Current state becomes selected, but if both states are equal, the resulting Current state will become deselected.

Logic Table (S=selected, D=deselected)

Saved Current Resulting Current State
S S D
D S S
S D S
D D D

The All lines option performs the XOR for all lines of the current list. The flag is set by this command. The following example selects the middle line of the list:

Example

; Leave line 3 selected
Set current list lMyList
Define list {lCol1}
For lCol1 from 1 to 6 step 1
  Add line to list {lCol1}
End For
Select list line(s) (All lines)
Save selection for line(s) (All lines)
Invert selection for line(s) {3}
XOR selected and saved (All lines)