QR Code for ereimer.net -- by Eugene Reimer 2010-Nov09

Since QR-Codes are the next big thing, I'm jumping onto the bandwagon by making a few of them.  The idea is to incorporate these into print- and billboard-media advertising to promote my website.  (This new thing works only in old media.)  Then whenever someone with a smartphone (camera- and QR-support-equipped) comes across it and scans it they'll be taken to my website.  Or, for the kind with complete contact-info, they'll have the choice of visiting my website, emailing, phoning, or having their GPS navigate to my address.  One of those is going onto my business-card.  Incidentally, QR Codes can also be used to display text to the user, or to provide just a phone-number, or just an email-address, etc, or to describe an event with date, time, location, description, or to provide the password for a WiFi connection. 

Fig-1: by qrcode.kaywa.com with Content-type:URL; 

contains:
Text:	http://ereimer.net/
Bytes:	41 36 87 47 47 03 a2 f2 f6 57 26 56 96 d6 57 22 e6 e6 57 42 f0 ec e6 e6 57 42 f0 ec

Fig-2: by zxing.appspot.com/generator with Content-type:URL; 

contains:
Text:	http://ereimer.net/
Bytes:	41 36 87 47 47 03 a2 f2 f6 57 26 56 96 d6 57 22 e6 e6 57 42 f0 ec 11 ec 11 ec 11 ec 11 ec 11 ec 11 ec 11 ec

Fig-3: by zxing.appspot.com/generator with Content-type:Contact-info; 

contains:
Text:	MECARD:N:Eugene Reimer;​URL:http://ereimer.net/;;
Bytes:	43 04 d4 54 34 15 24 43 a4 e3 a4 57 56 76 56 e6 52 05 26 56 96 d6 57 23 b5 55 24 c3 a6 87 47 47 03 a2 f2 f6 57 26 56 96 d6 57 22 e6 e6 57 42 f3 b3 b0 ec 11 ec 11 ec b3 b0 ec 11 ec 11 ec

Fig-4: by zxing.appspot.com/generator with Content-type:Contact-info; 

contains:
Text:	MECARD:N:Eugene Reimer;​URL:http://ereimer.net/;​EMAIL:ereimer@shaw.ca;​ADR:Winnipeg MB R2M0X3;;
Bytes:	45 d4 d4 54 34 15 24 43 a4 e3 a4 57 56 76 56 e6 52 05 26 56 96 d6 57 23 b5 55 24 c3 a6 87 47 47 03 a2 f2 f6 57 26 56 96 d6 57 22 e6 e6 57 42 f3 b4 54 d4 14 94 c3 a6 57 26 56 96 d6 57 24 07 36 86 17 72 e6 36 13 b4 14 45 23 a5 76 96 e6 e6 97 06 56 72 04 d4 22 05 23 24 d3 05 83 33 b3 b0 ec 11 ec 11 ec 11 ec 11 ec 11 ec 11 ec 11 ec 11 ec

If you lack a suitably-equipped smartphone you can read them using zxing.org/w/decode.jspx.  You'll notice that the two online QR-code-constructors I used produced different QR-codes for the exact same parameters; as read by the zxing.org reader, the byte-strings are different, yet the text-equivalent strings are identical.  This could be due to different Error-Correction levels, or to one using the "binary" and the other using the "alphanumeric" mapping.  Because QR-codes only come in certain discrete sizes, number of rows and columns, meaningless padding may be needed, and it looks as though strings of "11" and "ec" byte-pairs are used for such padding. 

For further reading, the Wikipedia article provides a good introduction, however to my surprise it does not provide the details.  For that one needs to purchase the English language specification from the ISO for 208-CHF (Swiss-Francs).  Or learn Japanese:-)  The Japanese specs are free.