Sonper,
Default (factory) setup for most barcode scanners is that they will add an additional suffix to the code.
This suffix is almost always a linefeed (as already mentioned).
The only barcode scanners I support are keyboard wedge, meaning that scanning a barcode is identical to tapping on the keyboard, so can't help you to a code example.
Does at it has a certain format that should be followed?
We need to consider 2 separate issues here:
1. (optional) additional characters (scanner dependent)
A scanner can be setup to add prefix (typically <Tab>) and suffix data to a barcode. For this, one need to reference the scanner manual
Some can even be setup to send barcode marker data (fe. Interleaved 3 of 9 requires a * or ! as start- and stop marker, which will normally be stripped by the scanner), or strip control numbers from the barcode
2. barcode format itself
Barcodes themself come in different flavours. From basically simple (alpha numerical data containing whatever) to normalized forms (fe. EAN, JAN, UPC), in which the barcode is build to set rules
However, this is only an issue when you want to process the barcode iso just reading them.
Diederik