What business is Google in? Collecting patents may be the overarching line of business. Google just got another patent, for its self-driving car project, this one for a method of shifting between self-driving and autonomous driving mode when it comes time to find a parking space. It shifts when it encounters a landing strip with information on parking. The info could be a QR code or some kind of radio communication to an onboard transceiver or a connected cellphone.

The patent was issued Dec. 13, 14 months after Google first disclosed its self-driving car. The patent is for “transitioning a mixed-mode autonomous vehicle from a human driven mode to an autonomously driven mode. Transitioning may include stopping a vehicle on a predefined landing strip and detecting a reference indicator.” In one scenario, it appears, a driver is looking for a parking space and drives over a giant QR code on a street or in a parking garage. The QR code might either have exact directions to a specific parking spot, or it might link to a parking garage database of which parking slots are open.

Google’s search is excellent at taking vague or unfocused queries and giving you good information online. This Google patent app, most commentators agree, is so vague it leaves you guessing exactly what they’re up to, sort of the opposite of what Google usually does. For instance, the cited indicator may be a big QR code in the road; it could be short-range radio such as DSRC (dedicated short range communications) that in a decade or so might be employed by cars to warn each other that they’re braking or shifting lanes or running a yellow light. Google doesn’t say QR code; it uses the term “reference indicator.”

Google tech isn’t the first to find parking spaces. Ford has it already with automated parking assist: Drive along the street slowly and sonar from front-rear-side sensors already on the car measure openings and tell you if there’s enough room to park the car you’re driving. It’s spot-on accurate (other than not being able to recognize parking spaces with fire hydrants) and it’s almost self-driving. You stop the car, put it in reverse, and Ford drives the car into the parking space in about 10 seconds. You do have to apply the brakes at the end.

This patent isn’t critical to self-driving cars. But it suggests that as Google builds a patent portfolio in the autonomous driving arena, some will be useful to a mainstream automaker doing its first self-driving car, and Google might want to engage in a little horse-trading: access to the Google patents in exchange for Google getting access to your dashboard and infotainment system.

See details on Patent 8,078,349, via TechRadar