Netscape Layout Extensions - HTML and XHTML: The Definitive Guide - page 1116

You can nest <multicol> tags, embedding one set of columns within an-
other set of columns. While infinite nesting is supported, more than two
levels of nesting are generally impractical and results in unattractive
text flows.
H.2.1.1. The cols attribute
The cols attribute is required by the <multicol> tag to define the number
of columns. If this attribute is omitted, Netscape 4 creates just one
column, as though the <multicol> tag isn't there at all. You may cre-
ate any number of columns, but in practice, more than three or four
columns make text unreadable on most displays.
The following example creates a three-column layout:
<h1 align=right>Temperature Effects</h1>
<multicol cols=3>
The effects of cooler weather on the kumquat's ripening process
vary based upon the temperature. Temperatures above 28&deg;
sweeten the fruit, while four or more hours below 28&deg; will
damage the tree. The savvy quat farmer will carefully monitor
the temperature, especially in the predawn hours when the mercury
dips to its lowest point. Smudge pots and grove heaters may be
required to keep the trees warm; many growers will spray the trees
with water to create an insulating layer of ice over the fruit and
leaves.
<p>
If a disastrous frost is predicted, below 20&deg;, the only recourse
may be to harvest the fruit early to save it from an assured disaster.
Kumquats may subsequently be ripened using any of the popular methane
and cyanoacrylate injection systems used for other citrus fruits.
Used correctly, these systems will produce fruit whose taste is
indistinguishable from tree-ripened kumquats.
</multicol>
Figure H-4 shows the results.