Wine breathes through the cork and fill levels diminish as it ages. Bordeaux and Burgundy shaped bottles have different fill level abbreviations, shown below.

Bordeaux Bottles 

In Neck (IN) A young wine or in exceptional condition.

Base of Neck (BN) The fill level for recent and older vintages. For wines over 25 years, this would indicate exceptional storage.

Top Shoulder (TS) Standard for wines over 10 years. For wines over 25 years, this indicates excellent storage conditions. 

Mid Shoulder (MS) About midpoint of the shoulder. Not unusual for wines over 30-40 years, but could suggest poor storage or early signs of cork failure in younger wines.

Low Shoulder (LS) Below the midpoint of the shoulder. Normally a wine over 40 years of age. 

Please note the comments are suggestive only.

Burgundy Bottles 

The Burgundy bottle shape does not allow for a level rating system and levels are described by measurements below the cork. 

<2 cm An excellent fill level for any wine age. 

<3-5 cm Standard for wines of 12 years and older. 3cm is excellent for wines of 5 years or older. 

<5-7 cm Not uncommon in wines over 30 years. 

Please note these comments are suggestive only.