In InDesign CS3,
a specific font weight or style (bold, italic, light, etc.) only survives the export to epub if you create a special character style for it that specifies both the weight / style and the font family.
The blend must contain a minimum of 10 % (by
weight) of the origin named, the label must clearly state the percentage, and the size of the
font on the label must adhere to
specific guidelines.