I contacted the BLM, and they helped me proceed in learning her age, color, where she was captured, how old at capture.  All from her freeze brand on the left of her neck.  These are called "alpha symbols".  They are a group of lines, that represent certain numbers. 
Solace is 16 years old, she was captured in Nevada ,on volcanic grasslands at the age of 6.  She is documented by Bureau of Land Management, as a bay, small mare with a whirl on her forehead.  (symbols are include above)
The BLM (bureau of land management) rounds up groups of Mustangs in large number, by helicopter.  I spoke to one of the government agent myself.  The herd is relatively "used to"  this process.  It is said to be humane, and the herd responds well.   They are taken to containment areas, brought up to date on vac's and worming's, and then sorted.  The healthy are returned to the herd.  The younger, weaker, or not so perfect are pulled out, branded, documented, vet checked, and sold.  Therefore insuring the continued health of the existing herd
There are two symbols to begin with, that represent BLM.  The next two symbols stacked over each other, are the birth year (92).  She is 16.  The following two symbols (56) represent area, in this case, Nevada.  Her personal ID numbers. 3463.
As of today,she had put on about 125 lbs.  I have had her for 18 days.  She made an emergency trip to the vet last night late with ACUTE PNEUMONIA. This means no oxygen going in the body.  Purple gums, tongue.   The Vet did everything possible, I encouraged her to not press nature.  Do the best , and then go to bed.  At 12:15 ,the Vet felt like she could do no more.   Severe heaving in the flank  indicated lung distress.  Several doses of miracle medicine didn't work.  High temp of 102.6, extremely low pulse of 50, Respiratory rate of 60, with acute wheezing, and strained nostrils. 
She also was reminded of Solaces' stamina ,  after several through-the-night checks, more medicine, and she was still alive.   A fighter, a survivor, the breed, the horse, the instinct.   Ultrasounds to the lungs, showed no abscesses or solid matter, no scars, no lesions.   A brush with death.  After 3 years, Solace has proven to be a loyal trail mare.  Occasionally, she struggles with respiratory distress brought on by allergies.  This can be controlled, but not healed.  For the human who owns her, they will have to appreciate her value, & personality  when she is feeling good.   And they will always administer her antihistamine & steroids,  on her bad days, taking care of her like a good friend, that is sick.            BeckyZavilla