What does (^?)* mean in this regex?

What does (^?)* mean in this regex?

References

Reference NO 1

http://stackoverflow.com/questions/1576789/in-regex-what-does-w-mean

Reference NO 2

http://stackoverflow.com/questions/12933034/what-does-this-regex-mean

Reference NO 3

http://stackoverflow.com/questions/4377480/what-does-this-s-regex-mean-in-javascript

Reference NO 4

http://stackoverflow.com/questions/17845014/what-does-the-regex-mean

Reference NO 5

http://stackoverflow.com/questions/16589130/what-does-0-9-mean-in-regex-perl

Reference NO 6

#EANF#

Reference NO 7

#EANF#

Reference NO 8

#EANF#