the detailed explanation about the array metadata.csv file

[Zhilong Jia]

Hello,

In the Array metadata.csv file, What's the meaning of column "individual_id"  ? Dose it mean for each drug (same period and dose), the duplicate and triple experiment? But it's strange that for rat in vivo single and repeat groups, some values of individual_id are large than 3 (triple experiments). Why? 

So, is there the detailed data column explanation for this file?

Thank you.

Zhilong  Jia