yes it is..
[root@proxy ~]# db yum_repositories show
addons=repository
EnableGroups=no
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons
Name=CentOS - addons
Visible=no
status=disabled
base=repository
EnableGroups=no
Exclude=kernel,kernel-smp,kernel-xenU,mkinitrd,mdadm,initscripts
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
Name=CentOS - os
Visible=yes
status=enabled
centosplus=repository
EnableGroups=no
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
Name=CentOS - centosplus
Visible=no
status=disabled
contrib=repository
EnableGroups=no
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
Name=CentOS - contrib
Visible=no
status=disabled
dag=repository
BaseURL=http://apt.sw.be/redhat/el4/en/$basearch/dag
EnableGroups=no
Exclude=freetype,htop,iptraf,rsync,syslinux
GPGCheck=yes
GPGKey=http://dag.wieers.com/packages/RPM-GPG-KEY.dag.txt
Name=Dag - EL4
Visible=no
status=disabled
extras=repository
EnableGroups=no
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
Name=CentOS - extras
Visible=no
status=disabled
smeaddons=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeaddons-7
Name=SME Server - addons
Visible=yes
status=enabled
smecontribs=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smecontribs-7
Name=SME Server - contribs
Visible=no
status=disabled
smedev=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smedev-7
Name=SME Server - dev
Visible=no
status=disabled
smeextras=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeextras-7
Name=SME Server - extras
Visible=yes
status=enabled
smeos=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeos-7
Name=SME Server - os
Visible=yes
status=enabled
smetest=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smetest-7
Name=SME Server - test
Visible=no
status=disabled
smeupdates=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeupdates-7
Name=SME Server - updates
Visible=yes
status=enabled
smeupdates-testing=repository
EnableGroups=yes
GPGCheck=yes
MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeupdates-testing-7
Name=SME Server - updates testing
Visible=yes
status=disabled
updates=repository
EnableGroups=no
Exclude=kernel,kernel-smp,kernel-xenU,mkinitrd,mdadm,initscripts
GPGCheck=yes
MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
Name=CentOS - updates
Visible=yes
status=enabled