According to the Rules Reference Guide on page 8
"The faction card signals which faction a player has chosen as the primary faction for his or her deck. An in-faction card bears the loyal or non-loyal faction symbol that matches the affiliation indicated by his or her faction card. For faction card anatomy, see Appendix II"
This is further explained in two additional sections within the RRG:
1) page 12: "Loyalty is a deckbuilding restriction that limits which cards can be used out-of-faction. A card is loyal to its faction if it has a scroll of parchment below its shield. A loyal card’s affiliation must match the affiliation of a deck’s faction card in order to be included in the deck. Certain card abilities (such as the Banner agenda cards) permit players to use non-loyal cards out-of-faction in a deck."
2) page 14: "Some cards are not affiliated with any faction; these cards are neutral. Any deck may include neutral cards. xNeutral cards are not considered to be in-faction or out-of-faction."
The understanding that I get from reading the above passages is that cards in a deck can be in-faction loyal, in-faction non-loyal, out-of-faction non-loyal, and neutral.
From this understanding can I safely assume that cards come in three flavors, 1) Loyal, 2) Non-loyal, 3) Neutral?
Thank you in advance!