The whole system essentially consists of three categories of plays: (1) Tebow gives the ball to a running back, (2) Tebow pretends to give the ball to a running back and throws it instead or (3) Tebow pretends to give the ball to a running back and then runs it himself.

WSJ: Waiting for Tim Tebow to Go

So the power dynamics underpinning the political system make all of the spending categories relevant to military modernization vulnerable to cuts in a defense downturn, even though Secretary Gates and his subordinates insist it is essential to maintain robust spending in those areas.

FORBES: How Politics Will Shape The Defense Downturn

And the regulators invented the Basel system of risk-weighted capital ratios, which stipulates different leverage ratios for different categories of loan, in theory to take account of the riskiness of those loans.

BBC: If banks are treated as naughty kids...

The eco-rating system assesses 15 specific criteria drawn from five general categories of sustainability attributes - attributes include the usage of environmentally preferable materials, minimization of hazardous substances, energy efficiency, responsible end-of-life treatment and environmentally-responsible manufacturing.

ENGADGET: AT&T's Eco-rating makes in-store debut alongside Pantech Renue

It may be that the objects of the solar system are too varied to be put into neat human categories.

NPR: Dwarf Planets May Finally Get Respect

But WPP's Spafax Networks has developed a system that works with Vistar, offering advertisers some ability to target specific categories of consumers.

WSJ: Auction System Helps Place Digital Outdoor Ads

The distribution segment, which produced 93% of first-quarter revenues, is a wholesaler of IT products across several categories, including IT systems, peripherals, system components, software and networking equipment.

FORBES: Magazine Article

First, under the Basel system that allows big banks with "advance" status to set their own evaluations of the riskiness of different categories of loan - the so-called risk weights - there is not enough consistency in how much capital different banks hold to cover similar risks.

BBC: UK banks 'still short of capital', says BoE