time_start 

timestamp 

Start time for the validity of a value 

time_end 

timestamp 

End time for the validity of a value 

variable 

text 

Variable name, e.g. load_avg 

str_value 

text 

Variable value, e.g. 0.34 

num_value 

double precision 

Variable value as number 

num_config 

double precision 

In case of consumables: Consumable maximum available value (configured value)