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When the feat is removed the reverse is applied if the operation was "+". "=" operations are not reset to the previous value when the ability is removed and the PC data must be manually adjusted by the player.
Example - Toughness feat
The feat "Automation" field has the value of: dbnumber:hp.miscperlevel:+1
When the feat is dragged to the character sheet, the automation field is read and the action carried out.
The action adds +1 to the current "level +/-" data for the PC hit points.
A small "+" sign is shown next to the Feat on the character sheet to indicate that this feat contains automation and has modified the character sheet.
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When this feat is removed from the character sheet the hit points current "level +/-" value will be reduced by 1.