What are the guidelines used for uppercase and lowercase inclined letters?

There aren't really specific "guidelines" for uppercase and lowercase inclined letters in a standardized way. "Inclined letters" usually refer to italicized text, and their capitalization follows the same rules as regular letters.

Let's break down the use of uppercase and lowercase in italics:

Italicization:

* Emphasis: You can italicize a word or phrase to emphasize it. For example, "The *really* important point is..."

* Titles of works: Titles of books, movies, songs, etc., are usually italicized.

* Foreign words: You can italicize words from other languages to highlight their foreignness.

* Scientific names: The scientific names of plants and animals are italicized.

Capitalization:

* Proper nouns: Just like regular text, proper nouns (names of people, places, etc.) are capitalized when italicized. For example, *New York City*.

* First word of a sentence: The first word of a sentence is always capitalized, even when italicized. For example, "*The cat sat on the mat.*"

* Titles: Titles of works are capitalized according to normal title capitalization rules, even when italicized. For example, *The Lord of the Rings*.

Example:

The *New York Times* reported that the *Titanic* sank in 1912. *The sinking* was a tragedy.

Key takeaway: The capitalization of letters in italics is consistent with the general rules of capitalization.

Note: Some style guides might have specific recommendations for italicizing text, but they are not standard rules.