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