2.1.729 Part 4 Section 3.8.17, family (Font Family)
a. The standard states that the values of the val attribute are defined by the XML Schema int datatype.
Excel restricts the value of this attribute to be at least 0 and at most 5.
b. The standard implies that the val attribute refers to character set.
In Office, the val attribute is interpreted as referring to the font family.