Someone posted this cut and paste in the Handmade forum; it is the updated Title Requirements page, and for all Marketplace listings. The question about “ or inches, etc., is covered:
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Product title requirements

Title requirements apply to all non-media products on all of Amazon’s worldwide marketplaces. The four criteria that could cause a non-media product to be search-suppressed are:

1. Titles must not exceed 200 characters, including spaces.
2. Titles must not contain promotional phrases, such as “free shipping”, “100% quality guaranteed”.
3. Titles must not contain characters for decoration, such as ~ ! * $ ? _ ~ { } # < > | * ; ^ ¬ ¦
4. Titles must contain product-identifying information, such as “hiking boots” or “umbrella”.

Failure to comply with these requirements may cause a product to be suppressed from Amazon search results.

TITLE LENGTH

Amazon generously allows 200 characters for titles, but for better title quality, you should aim for a maximum of 80 characters.

You may notice that different title lengths are listed in our category-specific style guides. These are guidelines only, not strict requirements, based on the preferred, typical title style for product listings in that category. For example, if a category-specific style guide recommends a title length of 150 characters, a product will not be suppressed from search for having a title over 150 characters long, as long as it stays within the limit of 200 characters.

TIPS

Good title quality is a key factor to ensuring a positive customer experience on Amazon. Below are additional tips for improving the quality of your titles. We will only search-suppress products with titles that violate one of the four requirements listed above, but we strongly encourage adherence to the following title standards:

• Titles should be concise. We recommend fewer than 80 characters.
• Don’t use ALL CAPS.
• Capitalize the first letter of each word, except for prepositions (in, on, over, with) or conjunctions (and, or, for) or articles (the, a, an).
• Use numerals: “2” instead of “two”.
• Don’t use non-language ASCII characters such as Æ, ©, or ®.
• Titles should contain the minimal information needed to identify the item and nothing more.
• Don’t use subjective commentary, such as “Hot Item” or “Best Seller”.
• Titles can include necessary punctuation, like hyphens (-), forward slashes (/), commas (,), ampersands (&), and periods (.).
• Titles can abbreviate measurements, such as “cm”, “oz”, “in”, and “kg”.
• Don’t include your merchant name in titles.
• Size and color variations should be included in titles for child ASINs, not the main title (see below).

TITLES USING VARIATION RELATIONSHIPS

In Variation Relationships, only the title of the parent ASIN is shown on the detail page. The title for the selected child ASIN will appear once the ASIN is added to the customer’s cart, so it is important to include the variation attributes like size and color in the title for the child ASIN.

• Example parent: Crocs Beach Clog
• Example child: Crocs Beach Clog, Lime Green, Men’s Size 8-9

EXAMPLE

Our research shows that customers scan-read results, meaning that titles don’t need to contain the exact phrase that customers are searching for in order to catch their eye. Longer titles are also harder to read than shorter titles, so the longer your title is, the more you risk losing your customer’s attention.

Think about a physical product on a supermarket shelf. Its title is simple and to the point. You only have a moment to catch the eye of a passing shopper. With online titles on Amazon, there’s no need to go on and on. Simply put, the title should reflect what is on the physical packaging of a product:

FAQ

1. Is title the same thing as product name? Yes.
2. What if my brand name contains a prohibited character, such as !, ©, ™, or ®? Ensure that your brand name is entered in the brand name field. If it contains a prohibited character, that character will be exempt from title requirements. Our aim is to keep titles free from characters such as !, ©, ™, or ®, but they may appear in the brand byline that appears on detail pages and in search results.
3. Does Amazon automatically put a brand name at the start of my title, or do I need to do that myself? We recommend that you begin a title with the product’s brand name in addition to ensuring the brand name field is populated. We have systems in place to add the brand name to the beginning of the title if it is missing, but providing it in the title ensures that it won’t be omitted due to unexpected issues.
4. What if my product doesn’t have a brand name? If your product is a generic brand with no brand name, you don’t need to state a brand name in its title. Instead, enter the word “generic” in the brand name field.
5. Are sellers notified in advance of listings being suppressed? No, not presently.
6. How do I know if my listings have been suppressed? Go to the Manage Inventory page and click Suppressed to see your suppressed listings.
7. What if another seller’s title violates the title requirements and causes a product that I’m also selling to become unsearchable? You can contact Seller Support to request a title correction if the other seller has not corrected it.
8. Do brand-registered products have the same title requirements? Yes.
9. Are title requirements the same for Fulfillment by Amazon (FBA), Seller Fulfilled Prime (SFP), and Merchant Fulfillment Network (MFN)? Yes. Title requirements are the same across FBA, SFP, and MFN.
10. Are model numbers recommended in titles? Refer to your category style guide. We recommend that model numbers should appear in titles for some categories, but not all of them.
11. Why don’t title requirements apply to media products? We don’t want to prohibit characters that might legitimately be part of a media product’s title. For example, book and movie titles commonly contain these characters.