sound diaplay
 

the mic level display in the camera is witout numbers.
does anyone know where is th 0 parameter?

Please note whether you are asking about the HM700 or 100.
Neither have numbers (never seen them on the VU meters). The following is for the 700, but I suspect the 100 is similar in the menus. - RTFM ;^)
These audio levels (mic or line) have menu settings which enable you to set the point in which the bold marker you use for setting standard level will be.
Note that with digital recording, we don't use 0 for a standard level. Levels are set much lower, because digital self noise is very low, but distortion when over-modulation occurs is much worse. The Audio reference level can be set to -12 or -20 depending on how conservatively you want to monitor your levels. This doesn't affect the levels themselves, which would be the same either way with a manual setting, merely the way you monitor them. A more experienced closely monitored level could be higher - a set and forget approach is probably better higher. Just remember, a red led probably means distortion is occurring, not the gentle compression first that analog recording had.