Kelvin Smith Library
Uniform titles (now more officially called Authorized Access Points) are systematized, agreed-upon titles for various works. When one catalogs an item, one transcribes information from the title page. Since music of famous composers is published all over the world, its title information can appear in various languages. And numbering systems can vary. (Example: at one point Dvorak's 9th Symphony was known as "No. 5"). Here's an example of varying titles for the same piece:
Lebedinoe ozero
Le lac des cygnes
Schwanensee
Swan lake
The uniform title for this is "Lebedinoe ozero" because Tchaikovsky was a Russian, and that was his original title. The catalog system has cross references, so that when a patron asks for "Swan lake", it will take her to "Lebedinoe ozero".
These get used in literature too. Consider this book:
Melville, Herman, $d 1819-1891. $t Moby Dick
Mobi Dik ili belyĭ kit (Moby Dick. $l Russian)
bai jing ji (Moby Dick $l Chinese)
The other use for uniform titles is to provide a tidy filing system. Using Beethoven's Eroica symphony as an example, we might see things like this on the title page:
Eroica: Symphony No. 3
Symphony No. 3
Third Symphony
3rd Symphony
Each of these will take you to a different place in the list of Beethoven's works. The ones beginning with a number (spelled out or numeric) are difficult because they place the symphony next to 3rd piano sonata, 3rd quartet, etc. But what if we call it:
Symphonies, no. 3, op. 55, E♭ major
It will file with the symphonies, and the symphonies will file in numeric order (the rest is just added information). There will also be a cross-reference from Eroica to get you there.