Ignore rules to reduce the number of options.
Sometimes when writing a script you want to have a specific line for one option only but not the others. For example, if you have a line that changes by day part (morning, afternoon or evening) and you want to talk about the weather only in the morning line, the Ignore check box lets you avoid having to create lines for every possible combination.
Without ignore, you would need to have 12 lines in the script:
With ignore, you can ignore weather for some of the day parts (for example Afternoon and Evening) and so end up with 6 lines:
|Afternoon||5 (with Weather set to ignore)|
|Evening||6 (with Weather set to ignore)|
You could take this even further if you only wanted to call out a snowy morning and not mention the weather in any other morning line.
|Morning||1||2 (with Weather set to Ignore)|
|Afternoon||3 (with Weather set to Ignore)|
|Evening||4 (with Weather set to Ignore)|
And as long as the Morning - Snow line (1) comes before the Morning / Ignore line (2) then a snowy morning will trigger that line. This is because we process rules from the top down and stop at the first true rule. (See the Greater Than post for more)