Tech Levels

In many Science Fictions RPGs Tech (Technology) Levels play a fairly important part. In Traveller Tech Levels are used to give the Player Characters information about what kind of equipment, weapons and culture they might find on a particular world. The GURPS system also uses Tech Levels, though as they were originally design Tech Levels were not to be mixed and matched in the same game, but rather intended to set the technology of the entire game world.
These Tech levels are primarily historically based for periods before the present technology level (which itself is a moving target,) and speculative for technology levels in the future.
I have always had two problems with tech levels quantified in this manner. One is that many devices would have been possible to fabricate at earlier historical periods than they appeared, if the people of the period had the prerequisite knowledge. For example the technological base to create computer chips did not exists in 1902. However all of the necessary technologies, principally metallurgy and photography, did exist for the creation of printed circuit boards. So crystal radios using printed circuit boards could have been manufactured in 1902.
Medical advancements, for example antibiotics, could have been produced easily by any culture who understood brewing, if they had known of their existence.
Future tech levels are entirely arbitrary, selected primarily to create some imagined level of game balance. The assigned level of any postulated superscience device is typically violated at will when required for the proposed game background. So in GURPS 3rd Edition teleportation is TL15, unless required for you game background, then its whatever TL your game world is. Good enough in the abstract, but not really useful on the ground.
My second problem with Tech Levels defined in this way is that the practice does not fit well in the real world. Take cell phones as an example. If we pick an arbitrary African country with little manufacturing capability, poor farming techniques, and abysmal medical treatment facilities what TL are they at? If we're using GURPS maybe TL5. But cell phone are ubiquitous and the local thugs always seem able to get the best and latest firearms. Those are TL7.
GURPS, which was first published in 1986, found its future tech books brushing up against real technology advances with night vision equipment listed at TL8 for prices double or triple real world prices just a few years later.
So if Tech Levels are arbitrary anyway and especially if collections of particular types of technology are arbitrarily assigned anywho let's assign Tech Levels in a top down way rather than a bottom up way.

.	Tech Level

. A Personal Transmat Portal technology, captured nanotechnology, terraforming. . B Commercial Transmat Portal technology. Force Field technologies. . C Hyperdrill technology, Hypercable systems. . D Gravity control, B/G engines . E Advanced cybernetics, medical robotics, power cells, medical suspension. . F Nuclear Fusion, Advanced computers, nanomaterials. . G Atomic, fossil fuel engines, electric distribution, aircraft . H Industrial revolution, mass production, steam power, telegraph. . I Advanced Iron Age . J Iron Age . K Bronze Age . L Non-technological . M Stone Age

The examples are neither all inclusive nor do they indicate the total exclusion of higher tech items on any world. They are an indication of the average technology available on that world. Obviously any world on a road had, at sometime in the past, a road crew outfitted at TL C or above come through or there would be no gate at that world. But a TL D or below world on a network road is dependent on workers from another world for parts and equipment to maintain that road. That becomes very important in the Midlands, where there is no Highland Department of Roads. Only worlds with a tech level of TL C and above can maintain their own portal gate.