Basic Metadata

Property Content Required
os:title

The title of your searchmercial as it should appear within the results.

YES
Notes:

Up to 40 characters permitted. (30 characters recommended)

For example:
<meta property='os:title' content='Atlanta Landscape Group' />

Compatible with : Open Graph

Open Graph example:
<meta property='og:title' content='Atlanta Landscape Services' />
os:headline

The headline (subtitle or title-tag) of your searchmercial as it should appear within the results.

YES
Notes:

An explanatory or alternate title, in addition to its main title. The headline is the text indicating the nature of the searchmercial. Up to 80 characters permitted (40 characters recommended)

For example:
<meta property='os:headline' content='Servicing the Atlanta metro area.' />
os:decription

The description of your object as it should appear within the results.

YES
Notes:

Up to 180 characters permitted. (80 characters recommended)

For example:
<meta property='os:decription' content='Providing unparalleled customer service.' />

Compatible with : Open Graph

Open Graph example:
<meta property='og:decription' content='Providing unparalleled customer service.' />
os:keywords

The keywords of your object separated by comma,
e.g., "keyword1, keyword2, keyword3".

YES
Notes:

Keep keywords relative to the call for action, up to 200 characters permitted. (Three keywords or search terms recommended)

For example:
<meta property='os:keywords' content='keyword1, keyword2, keyword3' />