What quick measure is that?

Hello

I've encounter such measure and I am not sure which one is that. I can see its not rolling average cause it computes another way. It claims to be 12 months rolling average. What this code does? calculates average from 12 months from datastamp (month-year lets say), so for instance on May 2022 it will give result of 12 months average value? or what

IF(
ISFILTERED('Fact Table'[Period]),
ERROR("Time intelligence quick measures can only be grouped or filtered by the Power BI-provided date hierarchy or primary date column."),
VAR __LAST_DATE = ENDOFMONTH('Fact Table'[Period].[Date])
VAR __DATE_PERIOD =
DATESBETWEEN(
'Fact Table'[Period].[Date],
STARTOFMONTH(DATEADD(__LAST_DATE, -12, MONTH)),
__LAST_DATE
)
RETURN
AVERAGEX(
CALCULATETABLE(
SUMMARIZE(
VALUES('Fact Table'),
'Fact Table'[Period].[Year],
'Fact Table'[Period].[QuarterNo],
'Fact Table'[Period].[Quarter],
'Fact Table'[Period].[MonthNo],
'Fact Table'[Period].[Month]
),
__DATE_PERIOD
),
CALCULATE(
SUM('Fact Table'[Value]),
ALL('Fact Table'[Period].[Day])
)
)
)