X-MMS-IM-Format The value of the X-MMS-IM-Format field is a list of parameters. You should not expect the paramaters to be arranged in any particular order, or for all the parameters to be included. As of summer 2003, the switchboard server requires FN to be the first parameter if it's included. If it is not, the switchboard will close the connectionwithout sending the message. This is presumably because of a font name bug that existed in older versions of the official client. Because server software constantly changes, third party clients should not rely on this. The official client always sends these fields in this given order: FN, EF, CO, CS, PF. TheRL parameter is included at the end if right-alignment is used, otherwise it is not included. The official client will accept parameters in any order. The official client always sends uppercase parameter names. Results are unpredictable when sending lowercase or mixed-case parameter names to the official client, but third party clients should still expect names to be in any case. Note that it is impossible to specify font sizes. A client is expected to determine the size of the font in all messages based on user preferences.
Font Name (FN) The FN parameter specifies a font name. The font name must be URL-encoded. For example, to have a font of "MS Sans Serif", you would have to specifyFN=MS%20Sans%20Serif. Font names are not case sensitive, and only spaces should be URL-encoded. URL-encoding other characters such as numbers and letters cause unpredictable results. If the receiving client does not have the specified font, it should make judgment based on the PF and CS parameters. Basically, the client should select whichever available font supports the character set specified in CS and is closest to the category specified in PF. If those parameters are not present, the client should just use a default font. There used to be a bug in the official client that caused it to crash upon receiving a message with a font that contained many %20s. To prevent this from happening, MSN patched the switchboard server so that it would close the connection if a principal attempts to do this.
Effects (EF) The EF parameter specifies optional style effects. Possible effects are bold, italic, underline, and strikethrough. Each effect is referred to by its first letter. For example, to make bold-italic text, include the parameter EF=IB or EF=BI. The order does not matter. Any unknown effects are to be ignored. The official client always sends effects in uppercase, and the results are unpredictable when it receives lowercase effects. If there are no effects, just leave the parameter value blank.
Color (CO) The CO parameter specifies a font color. Many versions of the official client limit you to sending only a few select font colors, but it is possible to specify any one of almost 17 million colors (24-bit color). The value of the CO field is a six-character hexadecimal BGR (blue-green-red, the reverse of the standard RGB order seen in HTML) string. The first two characters represent a hexadecimal number from 00 ff (hexadecimal for 255) for the intensity of blue, the second two are for green, and the third two are for red. For example, to make a full red color, send CO=0000ff. The official client always sends lowercase hexadecimal letters, but it will accept uppercase letters just the same. The official client also cuts off all leading zeros in outgoing messages. For example, 0000ff could be expressed as ff, but both are valid. Black may be expressed as simply 0. Other variations such as 7-character strings or unusual characters cause unpredictable results. If you are used to dealing with colors in HTML, just omit the hash sign and reverse the order of the colors. If you are not used to expressing colors in hexadecimal like this, you might findthis tutorial useful, but remember that MSN expresses colours in the order of blue-green-red and can omit leading zeros.
Character Set (CS) The term "character set" is quite ambiguous. The charset=UTF-8 in the Content-Typefield has a completely different meaning to the CS parameter in the X-MMS-IM-Formatfield. "Character set", as used in the X-MMS-IM-Format field, refers to the set of characters which a font must know how to translate into squiggles ("glyphs") on the screen. It's used mostly in the Windows world, and is increasingly a legacy from the time before Unicode was well supported. A font must support at least one character set, but may support more than one - for example, "Wingdings" supports the Symbol character set, "Verdana" supports the Western, Greek, Turkish, Central European, and Cyrillic character sets. Some background information on character sets is available on this MSDN page. Character sets are identified in the CS parameter with one or two hexadecimal digits (leading zeros are dropped by the official client and are ignored if present), representing the numerical value Windows uses for the character set. Here is the full list of Windows' predefined character sets:
0 - ANSI_CHARSET ANSI characters 1 - DEFAULT_CHARSET Font is chosen based solely on name and size. If the described font is not available on the system, Windows will substitute another font. 2 - SYMBOL_CHARSET Standard symbol set 4d - MAC_CHARSETLT Macintosh characters 80 - SHIFTJIS_CHARSET Japanese shift-JIS characters 81 - HANGEUL_CHARSET Korean characters (Wansung) 82 - JOHAB_CHARSET Korean characters (Johab) 86 - GB2312_CHARSET Simplified Chinese characters (Mainland China) 88 - CHINESEBIG5_CHARSET Traditional Chinese characters (Taiwanese) a1 - GREEK_CHARSET Greek characters a2 - TURKISH_CHARSET Turkish characters a3 - VIETNAMESE_CHARSET Vietnamese characters b1 - HEBREW_CHARSET Hebrew characters b2 - ARABIC_CHARSET Arabic characters ba - BALTIC_CHARSET Baltic characters cc - RUSSIAN_CHARSET_DEFAULT Cyrillic characters de - THAI_CHARSET Thai characters ee - EASTEUROPE_CHARSET Sometimes called the "Central European" character set, this includes diacritical marks for Eastern European countries ff - OEM_DEFAULT Depends on the codepage of the operating system
You should not assume that clients receiving your messages will understand all character sets (for example, Windows NT 3.51 has very poor character set support). MSN Messenger only allows you to specify a single character set in a CS field. This charset is arbitrary, but it is advisable to make it the one which will cause the most characters to be displayed correctly. The official client just offers the user a list of character sets supported by your chosen font.
Pitch and Family (PF) The PF family defines the category that the font specified in the FN parameter falls into. This parameter is used by the receiving client if it does not have the specified font installed. The value is a two-digit hexadecimal number. When programming with Windows APIs, this value is the PitchAndFamily value in RichEdit and LOGFONT. The first digit of the value represents the font family. Below is a list of numbers for the first digit and the font families they represent. This list was adapted from this MSDN page.
0_ - FF_DONTCARE Specifies a generic family name. This name is used when information about a font does not exist or does not matter. The default font is used. 1_ - FF_ROMAN Specifies a proportional (variable-width) font with serifs. An example is Times New Roman. 2_ - FF_SWISS Specifies a proportional (variable-width) font without serifs. An example is Arial. 3_ - FF_MODERN Specifies a monospace font with or without serifs. Monospace fonts are usually modern; examples include Pica, Elite, and Courier New. 4_ - FF_SCRIPT Specifies a font that is designed to look like handwriting; examples include Script and Cursive. 5_ - FF_DECORATIVE Specifies a novelty font. An example is Old English. The second digit represents the pitch of the font - in other words, whether it is monospace or variable-width. _0 - DEFAULT_PITCH Specifies a generic font pitch. This name is used when information about a font does not exist or does not matter. The default font pitch is used. _1 - FIXED_PITCH Specifies a fixed-width (monospace) font. Examples are Courier New and Bitstream Vera Sans Mono. _2 - VARIABLE_PITCH Specifies a variable-width (proportional) font. Examples are Times New Roman and Arial. Below are some PF values and example fonts that fit the category. 12 Times New Roman, MS Serif, Bitstream Vera Serif 22 Arial, Verdana, MS Sans Serif, Bitstream Vera Sans 31 Courier New, Courier 42 Comic Sans MS
Right alignment (RL) The RL parameter specifies whether a message should be right-aligned or not. It's value is1 if the message is right-aligned. The official client always omits this parameter unless the value is 1, but any other value does nothing and keeps the message left-aligned.
Examples X-MMS-IM-Format: FN=MS%20Sans%20Serif; EF=; CO=0; CS=0; PF=22 This X-MMS-IM-Format field expresses the MS Sans Serif font with no effects and a black colour. X-MMS-IM-Format: FN=Comic%20Sans%20MS; EF=S; CO=800000; CS=0; PF=42 This field expresses the Comic Sans MS font in a dark blue colour, underlined, and bold. X-MMS-IM-Format: FN=Verdana; CO=ff; EF=UB; PF=22; CS=cc This field expresses the Verdana font in full red colour, with the strikeout effect, and with a Cyrillic charset. The parameters are in an unusual order, but as long as FN is in the front, it's all right. X-MMS-IM-Format: FN=Courier%20New; EF=; CO=ff00ff; CS=0; PF=31 This field expresses the Courier New font in a bright magenta colour with no effects. X-MMS-IM-Format: FN=My%20Hebrew%20Font; EF=; CS=b1; PF=00; RL=1 This field expresses a made up font called My Hebrew Font with no specified colour, no effects, a Hebrew charset, and right-alignment. | 
