Mi imaginery of a oriented string is a line with two different (oposite) ChenPaton labels pasted in the extremes, say +...- while an unoriented one has the same label pasted in both extremes, say +...+ or -...- In this imaginery a vacuum loop for oriented strings would create two strings +...- and -...+ and they can only do a cylinder. On the other hand, unoriented strings can have a vacuum loop where the initial +..+ and -..- strings can rejoing to do a moebius strip. I ask that only opposite label can be joined when two strings join into one, and that a string must split to opposite labels. It seems to be adjusted to reason, as in any other case we would allow for self-aniquilation via an open string tadpole. I can recover the same imaginery if I draw a worldline in the border of the worldsurface, so that the signs + and - correspond to a label going forward or backward in time. So it seems pretty consistent. Now, if I keep on this idea, it happens that two unoriented strings can join to form an unoriented one: +...+ and -...- can join in +....(+-)....- and then evolve as a single +...- oriented string. Also, two oriented strings will always join to form a oriented string, and the join of an oriented plus an unoriented string will always form an unoriented one. And notice, an unoriented string will always break into an oriented string plus an unoriented one So what is happening here? Does unoriented string theory include the oriented string? I was used to hear the contrary: that we get the unoriented theory as a quotient of the oriented one.