[SOLVED] DimStyle : how to create a user one ?

Bonjour community,

I want to create my own dimension style base on this settings :

arrow 1 and 2   none,   
text override      " "            a space in order to have no dim value, 
ext line ext.     0.25,
ext line offset   0.25.
with dimension line visible 

How to create and save these settings ?
Thanks in anticipation and have happy Christmas.