Rule 1 extends to the first and last word of phrases separated by colons, so you should write "The Colon: An Important Mark, Yet...".NIVA follows the general rules for capitalizing words in document titles set out in The Chicago Manual of Style (with one minor exception-- see the note in rule 3):
- Always capitalize the first and the last word.
- Capitalize all nouns, pronouns, adjectives, verbs, adverbs, and subordinate conjunctions ("as", "because", "although").
- Lowercase all articles, coordinate conjunctions ("and", "or", "nor"), and prepositions regardless of length, when they are other than the first or last word. (Note: NIVA prefers to capitalize prepositions of five characters or more ("after", "among", "between").)
- Lowercase the "to" in an infinitive.
Following Chicago (not NIVA), one should capitalize the following words:
Do not capitalize the following words:
"In" as an adverb ("Bringing In the Sheaves", in contrast to "The Fish Was in the River")
Subordinating Conjunctions: "after," "although," "as," "because," "before," "how," "if," "once," "since," "than," "that," "though," "till, " "until," "when," "where," "whether," "while."
"In" as a preposition or as part of an infinitive ("He Wanted to Be Tall")
Short Prepositions: "at," "but," "by," "down," "for," "from," "in," "into," "like," "near," "of," "off," "on," "onto," "out," "over," "past," "till," "to," "up," "upon," "with."
Long Prepositions: "about," "above," "across," "after," "against," "along," "among," "around," "before," "behind," "below," "beneath," "beside," "between," "beyond," "despite," "down," "during," "except," "inside," "outside," "over," "past," "since," "through," "throughout," "toward," "under," "underneath," "until," "within," "without".
Co-ordinating conjunction: "and," "but," "or," "nor," "for," "so," "yet", "but," "for."
"But " and "for" are sometimes prepositions and sometimes conjunctions.
For such things as knowing which kind of conjunction is which, I like Heather MacFadyen's University of Ottawa site.
Now, let's think about how to choose which rules to follow. I think I prefer Chicago's style to NIVA's, though I waiver in my choice. I couldn't find any discussion of reasons for the rules. There are two levels of reasons.
1. Given what we are used to as 21st-Century Americans, what is best for us?
2. If we were starting from a clean slate, with no preconceptions, what rule would be best for us?
If we were starting with no preconceptions, capitalizing every word would be best. It saves thought for the writer, and doesn't make much difference to the reader. But we are used to having some words in lower case, and having some words be lower-case does help readability a little. One possible rule would be to alternate upper and lower case, like this: "A history Of punctuation For the Unlearned". But that looks too odd for us now. Another rule would be to capitalize only the important words, which is what many people do and roughly follows the conventional rule laid out above. Highlighting the important words aids in skimming titles. By this logic, the Chicago rule is better than the NIVA rule, because prepositions are unimportant words, no matter how long.
On the other hand, this logic also goes against the rule of not capitalizing "to" in infinitives. The infinitive "to go" is more like one word than two, and it starts with "t", not "g". It would perhaps make more sense to write "To go" than "to Go" in a title. Here are some examples
1. "To Be or Not To Be"
"To Be or Not to Be"
2. "The Way To Go Home"
"The Way to Go Home"
3. "Methods To Prevent or To Treat Malaria in Africa"
"Methods to Prevent or to Treat Malaria in Africa"
The Chicago Manual of Style collects a group of discussions of fine points of title capitalization. Its question and answer page has lots of fine points of style. This is *not* a FAQ's page, though. It does not have frequently asked questions-- quite the opposite. The Chicago Manual is searchable on the Web, but only if you pay for a subscription.