Grid Matrix is a Chinese 2D barcode, laid out as a grid of square blocks and made to hold Chinese text compactly. Outside China few scanners read it.

What it holds
Characters	Simplified Chinese - the characters of the GB 2312 standard - and letters, digits and symbols.
Length	Up to 2,751 digits or 1,836 letters.
Error correction	Automatic error correction, or from 10% to 50% of the symbol.
Readable text	None.

Settings
Size	Automatic size picks the smallest symbol the value fits, from 018x018 to 162x162 modules. When the value doesn't fit the size you chose, Labeljoy uses a bigger one.
Error correction	Automatic error correction depends on the size: 50% for the smallest, 40% for the next two, 30% above. With a fixed Size it's greyed out and set to Automatic error correction.
Character Set	Default character set is GB 2312, as the standard has it. UTF-8 holds any character, but only a scanner set up for it reads it right; ASCII and ISO 8859-1 (Latin-1) hold no Chinese.

Characters you can't type. A tilde followed by three digits is the character with that code - ~013 is a carriage return - and ~~ is a tilde.

The rest of the settings - quiet zone, color - are in the Barcode section.

What goes wrong
Input data too long.	The value doesn't fit even the largest Grid Matrix.
Some characters don't fit in this character set: choose UTF-8 in Character Set.	The value has a character the Character Set can't hold - with Default character set, a euro sign or a character outside GB 2312.