A missing-value placeholder marks an attribute that cannot be found in the source text. It keeps that attribute’s position in an extracted record without supplying a value the text does not provide. section 4.3.2 section 4.3.5
For a table extracted from emails, specify the attributes and their order, then instruct the language model to write <NA> whenever an attribute’s value is unavailable. This is different from a prompt-template placeholder, such as [Email]: [Email] is replaced before the prompt is sent; <NA> appears in the extracted output. section 4.3.2 section 1.4.1
A biography with no birth city
A biography extraction requests name, city of birth, and date of birth. When a biography snippet gives no birth city, its output row contains <NA> in that field rather than a concrete city. section 4.3.5
#1 Extract the following properties into a table: [List of attributes] #2 Text source: [Email] #3 Mark the beginning of the table with <BeginTable> and the end with <EndTable>. Separate rows by newline symbols and separate fields by pipe symbols (|). Omit the table header and insert values in the attribute order from above. Use the placeholder <NA> if the value for an attribute is not available.
The prompt specifies attribute order, table delimiters, and the exact marker to use for unavailable values. section 4.3.2
