Every skill has applications, which are sub-areas of the skill. If a skill check involves a certain application, it appears in parentheses, as in Perception (Spot). This is important when determining whether a hero can use a certain advantage or special ability. A check for Perception (Spot) means that the skill involves the specific application Spot. If a check doesn’t mention an application in parentheses, consider it a general use of the skill without any bonuses or penalties granted by a particular application.
Some skill applications are not immediately available. These new applications must be purchased via special abilities or advantages before the player can make checks in these areas. Remember, you can use SR for an application only after you purchase it.
Making a Check When You Don’t Have the Relevant Application
Sometimes a hero wants to make a skill check but does not possess the necessary application. For example, a party of heroes finds a discarded shield bearing a heraldic design. Identifying the heraldry on the shield requires a check on Etiquette (Heraldry & Family Trees). None of the heroes has the special ability Heraldry (which grants the new application Heraldry & Family Trees for the skill Etiquette), but two of the heroes have the advantage Noble I and therefore might have at least some knowledge of local heraldry.
If the GM decides that they can make a check without possessing the appropriate application, their checks suffer a penalty of at least 3. All other normal modifiers apply.
Core Rule page 186