Asymmetric Weights for end data? 5-term Henderson filter

What is the "asymmetric weights for end series" in a 5-term Henderson filter?

https://uk.mathworks.com/help/econ/seasonal-adjustment-using-snxd7m-seasonal-filters.html?#SeasonalAdjustmentUsingSnmSeasonalFiltersExample-4

I am trying to seasonally adjust a quarterly data series using the above example, which uses a 13-term Henderson filter aprox half way of the process. However I was unable to proceed since I do not know the values of an asymmetric weights for 5-term Henderson filter, unable to replace the 12-by-6 matrix in the example with a 4-by-2 matrix.

Does anybody know the values of the asymmetric weight for end series in a 5-term Henderson filter?

Note: I did get the stmmetric weights for 5-term Henderson filter (-0.073, 0.294, 0.558, 0.294, -0.073).

[Oren Schneorson]

You can find it in Shiskin (1967; a low resolution version is available on Google books) on page 63. Indeed he writes there that for quarterly data you want the 5-term option. See also:

Time Series Analysis: The Process of Seasonal Adjustment from the Australian Bureau of Statistics. They use 13-term option (asymmetirc weights) which exactly match Shiskin.

https://www.abs.gov.au/websitedbs/d3310114.nsf/4a256353001af3ed4b2562bb00121564/5fc845406def2c3dca256ce100188f8e!OpenDocument

Shiskin, J. (1967). The X-11 variant of the census method II seasonal adjustment program (No. 15). US Department of Commerce, Bureau of the Census.