dwp confusion

Hi, I was recently given a provisional offer for a decision making role for the dwp. Few days later I received an email saying they would like to offer me a different role working for the dwp in health disability services *ADHOC*. My question is what is ADHOC does it mean this position is not full time hours and only when required?
The original role I was offered had been a full time role. According to many sites ADHOC can mean they only require you when busy.
Can someone who knows please clarify if this new role is still full time hours?
Thanks in advance