improved documentation

docs/ics_format.txt

@@ -6,9 +6,41 @@ The iCalendar object is organized into individual lines of text,
 called content lines. Content lines are delimited by a line break,
 which is a CRLF sequence (CR character followed by LF character).
 
+Lines of text SHOULD NOT be longer than 75 octets, excluding the line
+break.  Long content lines SHOULD be split into a multiple line
+representations using a line "folding" technique.  That is, a long
+line can be split between any two characters by inserting a CRLF
+immediately followed by a single linear white-space character (i.e.,
+SPACE or HTAB).  Any sequence of CRLF followed immediately by a
+single linear white-space character is ignored (i.e., removed) when
+processing the content type.
+
+For example, the line:
+
+ DESCRIPTION:This is a long description that exists on a long line.
+
+Can be represented as:
+
+ DESCRIPTION:This is a lo
+  ng description
+   that exists on a long line.
+
+The process of moving from this folded multiple-line representation
+to its single-line representation is called "unfolding".  Unfolding
+is accomplished by removing the CRLF and the linear white-space
+character that immediately follows.
+
+When parsing a content line, folded lines MUST first be unfolded
+according to the unfolding procedure described above.
+
+--------------------------------------------------------------------------------
+
+Observation of different ics files from different sources
+---------------------------------------------------------
 
 ICS files from Microsoft Outlook differ from those that were created by Gnome Evolution.
-(semicolons are used instead of colons at some position)
+The order of "fields" seems not be standardized and differs between every application.
+
 
 Evolution
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