Please cite SAGA whenever you use it for your publications:

The tool allows one to merge the parts of multipart lines into lines. Invalid line parts with less than two points are skipped.

Name	Type	Identifier	Description	Constraints
Input
Multipart Lines	shapes, input	PARTS	The multipart lines.
Output
Lines	shapes, output	LINES	The merged lines.
Options
Epsilon	floating point number	EPSILON	The tolerance used to detect connected parts [map units].	Default: 0