There's a github page listing information about all Zotero fields and item types here: https://aurimasv.github.io/z2csl/typeMap.xml

When showing the various fields for each item type and what they mean, some of the fields are highlighted in blue. What does this mean? I think I need to understand this in order to solve a problem I'm having.

Here's an example:
https://s3.amazonaws.com/zotero.org/images/forums/u968689/xa5eqsaa67vyuq35e0wa.png

What is the highlighting telling me is special about the author and contributor fields in this item? Thanks!