The deal with FullSeason is that its not always a FullSeason, it could be a single episode with a episode title. For example:
```
Series.Title.S01.Episode.Title.Here.Quality-Releaser
```
That pattern unfortunately looks like a FullSeason and is classified as one but because it has an episode title then its actually a single named episode (and not always a special on season 00). The only way to know for sure is to search the episode backend. 

Regarding absolute numbers: Well I looked at the absolute numbers regexs and they didnt seem high confidence to me, as it i could see some false positives occurring there. So to be safe I just wrote the code to do a backend episode title lookup if no regular episode numbers had been parsed. It would be nice if Parse returned a "confidence level", a low confidence level would mean it would do a deeper DB match or perhaps ask the user.

Oh and the last check to see if any episodes actually exist in the nzbrone db seems silly but it has helped in a few cases. In one case in nzbdrone there were only 5 episodes for say season 4 of a series. But then two new special episode releases came out that had different numbering:  
```
S04E06.Xmas.Special, 
S04E07.New.Years.Special. 
```
So unfortunately NZBDrone has them in its db under:
```
 S00E02 Xmas Special
 S00E03 New Years Special
```
...and not season 4. So using the episode name search did correctly find the entries in the NZBDrone db and renamed the season and ep number correctly even though the release numbering was different.

The reality is, if a series clean name and an episode clean name both exist in the release title then its very high confidence to be that episode (about as high as a SxxExx, maybe higher if the numbering is whacked).