WWII White Service Stripe

Has anyone ever seen a white WWII Service Stripe?
My understanding is that the small red inverted stripes were worn on the lower right BD sleeve during WWII, but I have had two bits of conflicting information.
1) White Stripe indicated service in a previous war, i.e., WWI
2) White Stripe indicated wearer was a regular or TA soldier prior to war being declared.
Can anyone clarify please?
Many thanks,
Ken