punctuation - Parenthetical sentences

I have a colleague who, in his technical documentation, sometimes likes to put entire sentences, or sometimes entire paragraphs, in parentheses. This looks wrong to my eye, but I'm having difficulty articulating precisely why. Should I be more tolerant of this style, or is there a reason why comments in parentheses should generally be restricted to phrases within a sentence and not form larger units of text?

In case this isn't clear, here's an example, adapted from some text I'm reviewing:

By default, the template to be rendered will be $root/template. (Variable 
$root has a default value.)

(Previous versions of this program loaded templates from webapp/WEB-INF, 
but in this release these files have been moved out of the web application.)

I think the goal here is to de-emphasise the subsidiary information, but I think it would be clearer without the parentheses.

Answer

As you have indicated, the purpose of parentheses is to de-emphasize the enclosed material. There are a variety of techniques that can be used, depending on the style of the publication. Italics are also used to set off content as different (although they are often used for emphasis rather than de-emphasis). Changes in font are also used.

Parentheses can be placed around single words, phrases, complete sentences, or even complete paragraphs. There is nothing that specifically defines the limits, although using them around several paragraphs grouped together would be unusual.

The usual reason for using parentheses around a full paragraph is the need to logically cover the material at that point in the narrative, but to make sure that the reader understand that the content is not part of the main body of information. In fact, parentheses are often used in place of footnotes. While footnotes make clear that the information is an aside, they can be distracting or annoying to many people, and seem very formal.

This is really a style question, but the simple answer is no, there is nothing wrong with your colleague's approach. However, you are free to eschew this technique and find other ways to convey the relative importance of various content.