d2s_spec_keyvalue.md

 # D2Sphere Key / Value Specification
 
 ## Specification
+* key[X] is specified as a ASCII String as key non-quoted
+* keys with leading '_' like '_cell_rat' is reserved for predefined keys by D2Sphere
+* value[X] is specified as a ASCII String quoted (String,Hex or Base64)
+* single key/value pattern line must not exceed 4kbyte
+* each key/value set will be taged by time+date when written into DB or whith time+date+position given by $GPRMC 
+
+
 D2Sphere SFAL TCP connector incommig message
 ```
 $<sfal.data key1='value1' key2='value2' keyX='valueX'>" CRLF
-$ .... CRLF
+$GPRMC CRLF (optional)
+$ .... CRLF (optional)
 $<end> CRLF
 ```
 additional key value will be handeled as well for following SFAL data frames
@@ -23,6 +31,9 @@ PFAL to send key value to server
 $pfal,Tcp.Client.send,0,"<sfal.data key1='value1' key2='value2' keyX='valueX'>"
 ```
 
+## Predefined keys and their values and units
+* 
+
 ## Idea
 
 - Service type (4G LTE/UMTS...)