There are 9 levels of debug available, with higher numbers being more debug and level 0 being no debug. However not all levels are used by all components. Also if there is debug at a high level it is usually likely to be output at such a volume that it may obstruct normal operation. For this reason you should set the level carefully and cautiously until the degree of debug you wish to see is present. Scripts and the web interface only have one level so this is an on/off type option for them.