The RS, RST  and  RSV System
(R)eadability (S)trength (T)one / (V)ideo (image)
1- Unreadable.
2- Barely readable, occasional words distinguishable.
3- Readable with considerable difficulty.
4- Readable with practically no difficulty.
5- Perfectly readable.
1- Faint signals, barely perceptible.
2- Very weak signals.
3- Weak signals.
4- Fair signals.
5- Fairly good signals.
6- Good signals.
7- Moderately strong signals.
8- Strong signals.
9- Extremely strong signals.
1- Sixty cycle AC or less, very rough and broad.
2- Very rough AC, very harsh and broad.
3- Rough AC tone, rectified but not filtered.
4- Rough note, some trace of filtering.
5- Filtered rectified AC but strongly ripple-modulated.
6- Filtered tone, definite trace of ripple modulation.
7- Near pure tone, trace of ripple modulation.
8- Near perfect tone, slight trace of modulation.
9- Perfect tone, no trace of ripple or modulation of any kind.
1- Unreadable.
2- Barely Viewable,  just distinguishable.
3- Viewable  with considerable difficulty.
4- Viewable  with practically no difficulty.
5- Perfectly Viewable  .
Examples:
Voice  =  RS 59 or RS 59+ (if stronger than 9 then put Plus "xx"dB)
CW   =   RST 599  or RST 599X                                        or RST 599C    
                                              X = Rock steady signal !                     C = Signal with Chirp
SSTV, Hell =  RSV 595