[rules-users] Using variable in a drl file

Hi everyone, Can anyone guide me on how to declare a variable (e.g: a double variable) and use it throughout the drl file from top to bottom. almost similar to the function like semaphore. Thanks. Regards, Yen This correspondence is for the named persons only. It may contain confidential or privileged information or both. No confidentiality or privilege is waived or lost by any mis transmission. If you receive this correspondence in error please delete it from your system immediately and notify the sender. You must not disclose, copy or relay on any part of this correspondence, if you are not the intended recipient. Any opinions expressed in this message are those of the individual sender except where the sender expressly, and with the authority, states them to be the opinions of the Department of Emergency Services, Queensland.