What is Xmark ?  Xmark is a name of a company.

" Based in Ottawa, Ontario, Xmark is a wholly owned subsidiary of VeriChip Corporation."

The Xmark Company makes a product called "By Your Side".

"By Your Side" works with the VeriChip company's ACTIVE chips placed externally on mothers and newborns

called "HUGS " and "HALO", and works with the telemetry of the hospital where birth was given.

The telemetry is stringent. It monitors everywhere the newborn is.

Hi- Tech bracelet "Hugs and Kisses" -- June 9, 2007
The bracelets play a lullaby every time the baby is placed near mom. Also, the microchips -- embedded in a small music box on the plastic band -- are wired to a sophisticated system that locks down the maternity unit's elevators and stairwells if the baby is taken too close to the exits without mom.
The hospital's alarm will sound even if dad, who doesn't get a bracelet, tries to take the baby off the unit, if only for a walk, said Kate Austin, director of Women and Children Services at the Pontiac hospital.
The system, manufactured by the Delray Beach, Fla.-based VeriChip Corp., is controlled through computers at the nurses station. It is new this year at St. Joseph Mercy
The alarm will also sound if the bracelet loosens, or is cut off, she said. So far, there haven't been any lockdowns
http://www.detnews.com/apps/pbcs.dll/article?AID=/20070609/LIFESTYLE03/706090307/1040

HALO -- Fixed asset-tracking
Facility floor plan embedded in software provides visual indication of the location of a patient, staff member or asset.  HALO smoothly integrates into your facility’s day-to-day operations, and the system can be configured to send alarm notifications to one, multiple, or all networked workstations.
http://72.14.203.104/search?q=cache:huGKLywtqKEJ:www.swc.net/healthcare/security-verichip-halo.tpl+HALO+skin+sensing&hl=en&gl=us
&ct=clnk&cd=10

"By Your Side" is a follow-up program that works beyond the hospital, as we see it.

Though the information is not detailed, one can conclude that after the newborn is taken home, an external bracelet or device of some kind still remains on that child and maintains location-monitoring wherever Wi-Fi networks are established.

" Xmark ... the program is designed to provide customers with close and continuing support throughout the product life cycle, from initial purchase to implementation to ongoing use "

Currently, many cities in the USA are progressing toward Wi-Fi enabled communities, where wireless monitoring of ACTIVE external  chips can take place.

As we see it,  Xmark is taking the location-tracking from the hospital into the community...from the newborn to the developing child.

"The By Your Side program is the next step in our efforts to truly partner with our customers and provide the best possible infant protection. It’s a commitment for the long term that none of our competitors have made "

It will remain on that person as long as one sees value in being monitored and tracked.

"By Your Side" ( subsidiary "Xmark " ) -- June 25, 2007 --beyond the hospital and into your home
The By Your Side program provides Xmark's infant protection customers with an unmatched level of support to ensure success with their Halo or Hugs infant protection system. It is Xmark's commitment that every customer will be successful with infant protection.
The program has five main components:
1. Implementation Support,
2. Clinical Education,
3. Parent Education,
4. Public Relations
5. and Continuing Clinical Support.

Created with substantial input from current customers, industry experts and Xmark's clinical education staff, the program is designed to provide customers with close and continuing support throughout the product life cycle, from initial purchase to implementation to ongoing use.
Its market-leading infant protection, wander prevention, personal duress, and asset tracking applications are trusted by over 5,000 healthcare institutions worldwide to keep individuals safe

VeriChip's goal is to become the leading provider of RFID systems for people in the healthcare industry.
http://home.businesswire.com/portal/site/google/index.jsp?ndmViewId=news_view&newsId=20070625005101&newsLang=en
http://www.morerfid.com/details.php?subdetail=Report&action=details&report_id=3192&display=RFID
http://www.wirelessdevnet.com/news/2007/jul/06/news5.html

What is the subdermal VeriChip ?

The subdermal VeriChip is a Passive chip implanted under the skin ( Internal ) . It does not work with telemetry or Wi-Fi.
It can only respond when queried.