This appears to be a good excuse to hate on CSS Device Adaptation Module Level 1, let me quote from it so you understand the great sorrow I had when I needed to understand it:
This section is not normative. This section describes a mapping from the content attribute of the viewport element, first implemented by Apple in the iPhone Safari browser, to the descriptors of the @viewport rule described in this specification.
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Below is an algorithm for parsing the content attribute of the tag produced from testing Safari on the iPhone. The testing was done on an iPod touch running iPhone OS 4. The UA string of the browser: “Mozilla/5.0 (iPod; U; CPU iPhone OS 4_0 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8A293 Safari/6531.22.7”. The pseudo code notation used is based on the notation used in [Algorithms].
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If a prefix of property-value can be converted to a number using strtod, the value will be that number. The remainder of the string is ignored.
This appears to be a good excuse to hate on CSS Device Adaptation Module Level 1, let me quote from it so you understand the great sorrow I had when I needed to understand it:
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