The position of stitching, buttonholes, button. In a sewing machine you can, for example, change the position of the seam relating to the edge of the fabric.

Pattern for the placket.
I've never heard it used this way but it seems to match.
It's a strip of cloth - can be of different widths, usually has buttons or buttonholes, topstitching etc. It can also be used for polo shirts and fully opened shirts.

see
Placket - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Placket
In modern usage, the term placket often refers to the double layers of fabric that hold the buttons and buttonholes in a shirt. Plackets can also be found at the ...

All about Shirt Placket Styles
www.office-dress-shirts.com/shirt_placket.html
The shirt placket is located at centre-front of a mens dress shirt. ... The standard placket is a strip of fabric raised off the mens dress shirt front with stitches down ...

What goes into making a shirt? (heavily abridged) | Hugh & Crye Blog
blog.hughandcrye.com/making-a-shirt/
27 Mar 2011 – Broadly speaking, there are five steps in making a shirt – 1) Inspiration and Design, 2) Pattern drafting 3) Marking 4) Cutting and 5) Sewing and Finishing. ... and you can see the placket (the long rectangular portion) on the end. ... the set up of the marker – the CAD based layout of each piece of the shirt.

That's all I've found. The term is referred to the lenght of mouvement made by the "racla" and it takes from old techniques, when a "lastra di piombo" was used

Battuta (Tipografia)
E’ l’unità di misura della lunghezza del pezzo. In genere indica le lettere.
http://www.calendovisita.it/B__________514_TERMINI.html


In screen printing, a printing stroke (i.e., the movement of the squeegee across the screen fabric) in which the squeegee is pulled toward the front of the press when making an impression, commonly used on many European screen printing presses.
http://printwiki.org/European_Print_Stroke

Printing is carried out by lowering the printing head and by
activating the squeegee/flood bar stroke. When the printing stroke is completed,
http://www.cms-italy.it/PDF/Halley4.pdf
http://www.vidrioperfil.com/img/productos/productos-foto-amp...


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Note added at 2 days21 hrs (2012-04-17 11:46:12 GMT)
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Commonly, this is also referred as "print"

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Note added at 2 days22 hrs (2012-04-17 13:01:45 GMT)
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http://www.silkscreeningsupplies.com/product/MRAutoSTARTPlat

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Note added at 4 days (2012-04-18 15:50:09 GMT)
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features:
1. Adjustable screen frame holder
2. Variable printing stroke length
3. Single/Double stroke selection
4. Digital Stroke Counter
http://www.tootoo.com/s-ps/nano-print-plus-semi-automatic-sc...