What you show in your code is a static variable declared in the global code area, not a Global Static Value.

Each instance of a form/report/mass update has it's own global code area, so each client would have their own separate vflag.

Global Static Values are stored in the application itself. They are shared by all forms/report/code in all Clients using a particular application and they persist even if that application is closed and reopened. You access these using GlobalValue and @GlobalValue.

For a value that is available across all forms/reports/code, but only to a single client for a single session, use ClientLocalValue.