Use uppercase and no period in:

• buttons
• checkboxes
• radio buttons
• menu items

Don’t	Do
.PDF, .CSS, .HTML	PDF, CSS, HTML

Use lowercase and specify a noun after the extension in full sentences in:

• tooltips
• notices
• messages

Don’t	Do
Add a DOCX file. Save your file in the pdf file format.	Add a .docx file. Save your file in the .pdf file format.