Transaction variant is a usefull tool to change field status in screens of transaction or report and it's also usefull in authorization.
Below is use guide of SAP Wiki.
http://wiki.sdn.sap.com/wiki/display/Snippets/Transaction+Variant+-+A+Step+by+Step+Guide+for+Creation
Below is use guide of SAP Wiki.
http://wiki.sdn.sap.com/wiki/display/Snippets/Transaction+Variant+-+A+Step+by+Step+Guide+for+Creation