Time Dimension ID YYYY.INP

Hi what is the purposes of the member Time ID with YYYY.INP.

I thinks it's come from the initial installation but we don't use it. But year after year we create the member ID 2014.INP , 2015.INP etc...

I saw it can be used for planning at year level ???

In my case the .INP don't have a parent or child but I have 2014.TOTAL and all the month are the childs of this parent.

If I keep it in which case can I used it ??? planning at year level ? Use it in budget allocation ?

Thanks