5 Month Visa ?

[webfact]

I am in the proccess of 1y visa extension. Last time another 3mont extension was granted and stamped in my PP together with an extra stamp which reads something with 5 month in Thai.

attached in my PP is a paper which reads:

In cases of under condition 5 month visa-extension of the work permit is to be for the same period....

.... must be submitted to the Immigration Bureau before the 5 months visa expires.

What is the 5 MONTH VISA? A new category? Thought Immigration grants 1 year extensions?

Thanks in advance for clarification