Determining the fragmentation of Indice

From http://www.sql-server-performance.com/2011/index-maintenance-performance/

SELECT
    OBJECT_SCHEMA_NAME(FRAG.[object_id]) + '.' + OBJECT_NAME(FRAG.[object_id]),
    SIX.[name],
    FRAG.avg_fragmentation_in_percent,
    FRAG.page_count
FROM
    sys.dm_db_index_physical_stats
    (
        DB_ID(),    --use the currently connected database
        0,          --Parameter for object_id.
        DEFAULT,    --Parameter for index_id.
        0,          --Parameter for partition_number.
        DEFAULT     --Scanning mode. Default to "LIMITED", which is good enough
    ) FRAG
    JOIN
    sys.indexes SIX ON FRAG.[object_id] = SIX.[object_id] AND FRAG.index_id = SIX.index_id
WHERE
    --don't bother with heaps, if we have these anyway outside staging tables.
    FRAG.index_type_desc <> 'HEAP' AND
    (
    --Either consider only those indexes that need treatment
    (FRAG.page_count > @PageCount AND FRAG.avg_fragmentation_in_percent > @MinFragmentation)
    OR
    --or do everything when it is MaintenanceDay
    @IsMaintenanceDay = 1
    )
ORDER BY
    FRAG.avg_fragmentation_in_percent DESC;

@PageCount: Default value is 128. Anything below this threshold we ignore. The benefits here do not justify the efforts.
•@MinFragmentation: This defaults to 10%. Anything below 10% is ignored. We couldn’t observe any significant performance hit with fragmentation levels < 10% given our workload.
•@IsMaintenanceDay: Once a week we have a maintenance window, in which we can maintain all indexes.