The 1st element CONDITION is a sexp which consists of following.
-1. Functions which accept argument FIELD-NAME and VALUE.
+1. Functions which accept arguments FIELD-NAME and VALUE.
FIELD-NAME is a symbol of the field name.
`equal' ... True if the field value equals to VALUE.
VALUE can contain \\& and \\N which will substitute
from matching \\(\\) patterns in the previous VALUE.
-2. Functions which accept any number of arguments.
+2. Functions which accept an argument SIZE, SIZE is some number.
+
+`<' ... True if the size of the message is less than SIZE.
+`>' ... True if the size of the message is greater than SIZE.
+
+3. Functions which accept any number of arguments.
`or' ... True if one of the argument returns true.
`and' ... True if all of the arguments return true.
-3. A symbol.
+4. A symbol.
When a symbol is specified, it is evaluated.