Each row represents a parameter for the components. The row starts with the number of the parameter (starting with 0, which is the rate). Then it has a list of classes separated by colons if the parameters must have equal values, and commas if they can have separate values. A full stop <.> between two values indicates a comma-separated list of all values between them, that have not already been listed. A dash <-> indicates a colon-seperated list. If there is no first value, zero is assumed. If there is no second value, the number of components minus one is assumed (so that all later components are included).
Each class can be followed by a range in the form (-3,0), which
indicates that the variable in question is constrained to lie between
-3 and 0, in this case. In this range, either the first or second
element can be empty (indicated either by a space or by the underscore
<_> character). This indicates that there is no lower or upper
bound.
If the parameter number in a row is a full stop <.>, this means that all rows between the one above and below that do not already have patterns should follow this pattern (or the pattern of the row above if there is no pattern). If the parameter number is a '|', it indicates that the groups in the rows above and below should be merged. Rows can be separated with a semicolon instead of an end of line. This is useful for inputing the mixture as a string, rather than writing a separate file for very simple mixtures.
Some parameters within a row can be declared to follow a distribution. The parameters involved in the distribution begin with the <<> character, followed by the name of the distribution to be used, then a space, then the parameter classes involved in the mixture, using the normal format. Finally the <>> character is used to end the distribution.
An example of specifying a distribution is: 2 <beta 0.2,3-6>,7-.
[Some aspects of this don't work quite as described yet. This
shouldn't be a problem for usual mixture files, only if the mixture
file is specified in a strange way. If you list the rows and entries
in increasing order, there should be no problems. Things like
5 7-5,3.6,0:2;|;.;2, however, are not guarenteed to work correctly.]
For examples, see the file mixture. See also the mixture strings in the file models.