Creating a field with a Key of MUL

 When you use the Desc table command, there is a column termed 'KEY" in which each field can be nothing, PRI, or MUL.  When I create a table what is the syntax to make a field have a Key of MUL ?
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Referencing   (page is dead, google cache is available):

"MUL means that the key allows multiple rows to have the same value.  That is, it's not a UNIque key. "
you can create "MUL" key this way:
create table example (
 nonunique int(9),

usual use is when you have 1:N or N:N relation between tables, for example:
create table colors (
 id_color int(5) unsigned not null auto_increment,
 name varchar(50),
 primary key(id_color)

create table cars (
 id_car int(9) unsigned not nul auto_increment,
 carname varchar(100),
 id_color int(5) unsigned not null,
 primary key(id_car),

relation between colors and cars is 1:N - so id_color is multiple key in cars table

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