Microsoft and some other "standards" differ in whether a "paragraph" break is a CR LF or a LF CR. Either a CR LF CR LF or a LF CR LF CR will always contain at least one "correct" pair, and the others will be "mostly ignored," or in some cases will contain two correct pairs in which case both will work.

I think this time it is the HTML spec. Here is part of 4.01 section 17.13.4 "Form content types",

application/x-www-form-urlencoded

This is the default content type. Forms submitted with this content type must be encoded as follows:

1 Control names and values are escaped. Space characters are replaced by `+', and then reserved characters are escaped as described in [RFC1738], section 2.2: Non-alphanumeric characters are replaced by `%HH', a percent sign and two hexadecimal digits representing the ASCII code of the character. Line breaks are represented as "CR LF" pairs (i.e., `%0D%0A').