This part of JIS Z 83139 specifies the Roman letters, numbers, and symbols (hereinafter referred to as letters) used in technical drawings and related documents. These regulations basically concern letters using templates, but they also apply to other methods such as handwriting.
JIS Z 8313-1:1998 history
2000JIS Z 8313-1 ERRATUM 1:2000 Technical drawings -- Lettering -- Part 1: Currently used characters (Erratum 1)
1998JIS Z 8313-0:1998 Technical drawings -- Lettering -- Part 0: General requirements