A title is always required.
Titles for Digital Collections
To avoid unintended sort order results in your collection, be consistent with the use of capitalization and punctuation; carefully consider how dates are used as portions of titles; and when using numbers in titles, add leading zeros so that all numbers have the same amount of digits. (If there are fewer than 10 items, you can use 1-9; if there are between 10-99, use 01-09; if there are 100-999, use 001-099; etc.). See https://www.asciitable.com/ for additional information.
<mods:titleInfo usage="primary">
<mods:title>Huey P. Long Signing Papers in Pajamas</mods:title>
</mods:titleInfo>
<mods:titleInfo usage="primary">
<mods:title>Official letter from the Directors of the Company of the Indies, Paris,
to Monsieur [Jean] Morin, Cap-Français, [Saint-Domingue]</mods:title>
</mods:titleInfo>
<note type="titleSrc" displaylabel="Title Source">Title provided by cataloger.</note>
Title and uniform title
<mods:titleInfo usage="primary">
<mods:title>150 Psalms</mods:title>
</mods:titleInfo>
<mods:titleInfo type="uniform" authority="naf" valueURI="http://id.loc.gov/authorities/names/n79056804">
<mods:title>Bible. Psalms</mods:title>
</mods:titleInfo>
Title with alternative title
<mods:titleInfo usage="primary">
<mods:title>Jambalaya Yearbooks 1898</mods:title>
</mods:titleInfo>
<mods:titleInfo type="alternative">
<mods:title>Jambalaya (New Orleans, La.)</mods:title>
</mods:titleInfo>
Original title with non-sorting characters and translated title
<titleInfo usage="primary" lang="spa" displaylabel="Title - Spanish">
<nonSort>El</nonSort>
<title>camino infinito</title>
</titleInfo>
<titleInfo type="translated" lang="eng" displaylabel="Title - English">
<title>Endless road</title>
</titleInfo>
<note type="titleSrc" displaylabel="Title Source">Title translated by cataloger.</note>
Complex uniform title with part name and number
<mods:titleInfo type="uniform" authority="naf" valueURI="http://id.loc.gov/authorities/names/n2012045495">
<mods:title>Humoreske</mods:title>
<mods:partName>Opus 12</mods:partName>
<mods:partNumber>No. 1</mods:partNumber>
</mods:titleInfo>