The document I linked to has a section entitled "DGI eligibility requirements" with specific items in it:

"2. DGI Eligibility Requirements. In order to participate in the DGI program, an eligible
pilot under Paragraph 1 above must, at the time his name is submitted to Delta for a DGI,
comply with the following:
a. Meet all of Delta’s established objective hiring criteria and requirements in place at
the time the interview is offered and complete all applicable forms, paperwork or
other application processes required by Delta of other applicants.; and
b. Participate in the full Delta selection process in place at the time the interview is
offered; and
c. Agree to the release of all employment and training records when requesting to
participate in the guaranteed interview program; and
d. Served at least twenty-four (24) months in active status as a Captain for Endeavor.
e. For the purpose of determining whether a pilot has met this requirement, a Pilot will
be deemed to be in active service unless he is on a medical leave, other unpaid leave
of absence and/or Long Term Disability, military leave of greater than thirty (30)
days, Furlough, periods of de-qualification that cause the pilot to be removed from
pay status and that are not caused by the Company, suspension without pay, or Time
Off Without Pay. A pilot who is on ESL or approved FMLA will be considered to be
in active service. A pilot who is Occupational Injury Leave (OJI) will be considered
to be in active service for the first ninety (90) days from the date of injury. A Pilot who is not in active service for more than fourteen (14) days in a month will not
receive credit for that month toward the twenty-four (24) month commitment;"