Turkmenistan Transit Visa - date specific or not?

[Nicoit]

I think that we should update the official page about the Turkmen visa, I applied in Rome and picked up in Theran, my visa was date specific but they asked me the dates at the moment of the pickup, it seems that is the standard now.
So the only way to enter when you want is to pick up the visa at the border, Rome embassy didn't provide me any official document/email, they have just given me a code at the phone, so I was not feeling comfortable to go at the border just with a code saved in my phone notes.