Why are the brackets not in the barcode?

Brackets are only in the printed text. In the bars, AIs are separated by the FNC1 character, which the generator inserts.

Can I put any text in (10)?

Letters, digits and the GS1 set of punctuation: ! " % & ' ( ) * + , - . / : ; ? and _. Brackets cannot be used inside a value here.

GS1-128 barcode generator

GS1-128 carries a product number together with batch, expiry, weight or a shipping container code, each marked by an Application Identifier (AI) in brackets. The generator checks each AI's length, dates and check digits before drawing the code.

Size with quiet zones136.1 × 38.1 mm5.36 × 1.50 in

Larger than common sticker labels: use a custom label size or a smaller module.

Encoded: (01)09521234543213(17)271231(10)LOT42

136.1 × 38.1 mm

How to use it

Write each AI in brackets followed by its value, for example (01)09521234543213(17)271231(10)LOT42.
Leave out the check digit of a GTIN (01) or SSCC (00) and it is added for you.
Dates are YYMMDD. Day 00 in (15) or (17) means the last day of that month.
Keep the module at 0.495 mm or more and the bars at least 31.75 mm tall on logistics labels.

Common Application Identifiers

AIs accepted here (selection)
AI	Meaning	Format
(00)	SSCC, serial shipping container code	18 digits with check
(01)	GTIN of the item	14 digits with check
(02)	GTIN of items in a logistics unit, with (37)	14 digits with check
(10)	Batch or lot	up to 20 characters
(11), (13)	Production, packaging date	YYMMDD
(15), (17)	Best before, expiry date	YYMMDD
(21)	Serial number	up to 20 characters
(30), (37)	Count of items	up to 8 digits
(310n)	Net weight in kg, n decimals	6 digits
(400)	Purchase order number	up to 30 characters
(410)–(416)	Location numbers (GLN)	13 digits with check
(420)	Ship-to postal code	up to 20 characters
(90)–(99)	Internal data agreed with partners	up to 30 / 90 characters

Limits

A GS1-128 code holds at most 48 data characters (AIs included) and should be no wider than 165 mm. Split longer data across two codes.

Questions

Why are the brackets not in the barcode?: Brackets are only in the printed text. In the bars, AIs are separated by the FNC1 character, which the generator inserts.
Can I put any text in (10)?: Letters, digits and the GS1 set of punctuation: ! " % & ' ( ) * + , - . / : ; < = > ? and _. Brackets cannot be used inside a value here.