Skills such as Area Knowledge, Current Affairs (Regional), Geography (Regional), and History require specialization to specific places and times. In reality, this kind of knowledge is never 'clear cut', and tends to spill over into related areas. The following penalties apply when you wish to use such a skill outside your specialty.

For an area far from your 'stomping grounds', use the penalties under Long-Distance Modifiers. However, the speed at which knowledge propagates increases as progressively more powerful tools for managing information appear: printing press, telephone, television, computers, faster-than-light radio, etc. To reflect this, at TL5 and above, the GM may choose to roll 3d against TL+1 (e.g., 9 or less at TL 8) to determine whether you are familiar with the distant region from TV, the Internet, etc. On a success, you may ignore all distance penalties. (The GM might also wish to use this rule to determine whether a character's Reputation is known far from home in a high-tech setting.)

Time is usually only a concern for History skill - but it could also apply to Area Knowledge skill in a time-travel game, or if someone has been away from home for a long time. Use the Long-Distance Modifiers once again, substituting years for miles. For each point of tech-level difference, double the time modifier (a two-TL difference would be x4, etc.) This is because societies change drastically on all levels when technology increases.

“Area classes” are defined under Area Knowledge skill: Neighborhood; Village or Town; City; Barony, County, Duchy, or Small Nation; Large Nation; Planet; Interplanetary State; and Galaxy. Area class becomes important in campaigns that involve a lot of travel. We assume here that the smaller areas are contained within the larger ones.

If you have specialized in a larger area and want information about a smaller area within it, the penalty is -2 for one class of difference, -4 for two, -8 for three, and so on, doubling each time.

If you have specialized in a smaller area and want information about a specific locale within the larger area containing it, the most appropriate solution is usually to use the distance penalties described above. However, questions having to do with the entire large area use a flat -2 per difference in levels.

Example: Someone with Area Knowledge (Earth) would be at -8 - due to three classes of difference - to know the mayor of Los Angeles. However, someone with Area Knowledge (Los Angeles) would be at -4 to know the location of Mount Rushmore. The same person would be at -10 to know the location of the Library of Congress in Washington, D.C.; the Library of Congress has more to do with Washington than with the United States as a whole, and it's more appropriate to resolve the question by considering distance.

Note that in a setting with multiple planes of existence, Area Knowledge skills for one reality can be dangerously unreliable in another. The GM decides the penalty that he will apply when you try to apply your knowledge of your San Francisco to his version.

For skills that require the Long-Distance Modifiers table, this is the table used to determine range penalties. If the distance falls between two values, use the higher.

Add another -2 per additional factor of 10.

Biology, Geology, and Meteorology require you to specialize by 'planet type', as does the 'Physical' specialty of Geography. If you do not specify a planet type, your native planet type is assumed - so if the campaign will never leave your home world, save space, and just write 'Geology', 'Biology', etc. GURPS sorts planets into six broad categories for these purposes.

Earthlike: Essentially, all habitable worlds.

Gas Giants: Jupiter/Uranus types.

Hostile Terrestrial: Venus types.

Ice Dwarfs: Comets and small moons composed almost entirely of snow or ice.

Ice Worlds: Rock worlds covered by a frozen 'ocean.'

Rock Worlds: Most moons, asteroids, etc.

Unless otherwise specified, all planet-type specialties for a given skill default to one another at -4.

The following skills deal with the health, function, or vital points of living beings: Body Language, Diagnosis, First Aid, Physician, Pressure Points, Pressure Secrets, and Surgery. These skills work as written when working with members of your species. When dealing with a member of another species, apply the following modifiers.

Species with similar physiology: -2 (human vs. elf) to -4 (human vs. troll).

Species with very different physiology, but still from your world: -5. This includes all normal animals.

Utterly alien species: -6 or worse (GM's option.)

Machine: No roll possible! These skills do not work at all on creatures with the Machine meta-trait.

A successful roll against a suitable skill lets you avoid these penalties. This roll is usually against the relevant racial specialty of Physiology, although Biology-4 suffices for common animals.

When choosing technological skills for your character, it can be helpful to bear in mind that such skills govern three distinct classes of activity:

Design. An inventor, gadgeteer, or mad scientist requires skills that let him design and build new inventions, redesign existing ones, and deduce the function of (and reverse-engineer!) unknown technologies. The key skill here is Engineer - specialized in the inventor's fields of interest - but Bioengineering (for biotechnology) and Computer Programming (for software) are equally appropriate.

Repair. A craftsman or technician needs skills that enable him to troubleshoot and repair known devices, perform major overhauls and upgrades, install new equipment, and customize existing gear. The most important skills of this type are Armoury, Electrician, Electronics Repair, Machinist, and Mechanic.

Use. A detective, soldier, spy, or similar professional needs skills that let him operate specialized equipment, conduct routine maintenance on his gear, and identify common makes and models (and their strengths and weaknesses.) Such skills include Computer Operation, Electronics Operation, Environment Suit, Explosives, vehicle skills (Crewman, Driving, Shiphandling, etc.), and weapon skills (Artillery, Guns, etc.)

These skills form 'design-repair-use triads'; e.g., Engineer(Electronics)-Electronics Repair-Electronics Operation for electronic devices, Engineer(Vehicle)-Mechanic-Driving for vehicles, and Engineer(Small Arms)-Armoury-Guns for firearms. Cinematic adventurers with great depth of knowledge often have all three skills in a triad!