Where goes the undeclared variables in VBA

Question

I try to understand what (and how) does some old VBA code.

I have a Sub, and I have a variable that is not declared in that Sub.

The Option Explicit is set to False.

Should I consider that variable a global one? Didn't found that info in the VBA docs...

Sub test1()
    x = "test one"
End Sub

Sub test2()
    x = "test2"
    Call test1
    MsgBox (">'" + x + "'<")
End Sub

there is no way to navigate to the definition of an undeclared variable