Update of Fed mandate(2020) - "shortfalls of employment" In this Fed link, it's stated that 1 of the most important changes in the document describing the Fed mandate/framework, is

On maximum employment, the FOMC emphasized that maximum employment is
a broad-based and inclusive goal and reports that its policy decision
will be informed by its &quot;assessments of the shortfalls of employment
from its maximum level.&quot; The original document referred to &quot;deviations
from its maximum level.&quot;


Does &quot;maximum employment&quot; mean potential rate of employment?
In what way does the substitution of &quot;deviations&quot; for &quot;shortfalls&quot; change the mandate?
First, this is not change in mandate, Fed cannot just change its mandate unilaterally, as the mandate is given to Fed by US congress (see this Fed Richmond essay on that)  this is just change in its goals in pursuit of their current mandate.

Does &quot;maximum employment&quot; mean potential rate of employment?

According to Fed 'maximum employment' means:

Maximum employment is the highest level of employment or lowest level of unemployment that the economy can sustain while maintaining a stable inflation rate.

So taken at face value this would mean that by 'maximum employment' they mean  non-accelerating inflation rate of unemployment (NAIRU).

In what way does the substitution of &quot;deviations&quot; for &quot;shortfalls&quot; change the mandate?

It does not change the mandate at all, it changes the Fed's goals in pursuit of their current mandate. A deviation by definition means either positive or negative change from the target (eg unemployment being either above or below their target). If they only look at a shortfall from the target level that would mean they are only concerned if unemployment is above the target but not if it is below.