Not sure what you mean. Are you referring to the 'e' next to the volume?
eg; 275ml e
This large lower case 'e' stands for 'european' and means that the volume conforms to European regulations on packaging weight variances.
For example, if you bought a 1kg bag of rice, you would expect it to contain at least 1kg of rice or. if you are lucky, a bit over. Due to the nature of the industrial process, packaging plants can not always perfectly measure the exact weight/volume/etc. It is in the manufacturer's interest to be as close to the target weight as possible - but not under ('underselling') or over (giving it away!)
The European regulations stipulate the VARIANCE ie the max limits above and below that the final weight can vary by from the stated weight and the 'e' shows the product conforms to these standards.
You're now going to tell me that your question was about something else.... ;-)