The Service record cards were taken from many, many sources. In the case of a wounding or sickness often a muster roll listed the soldier only as sick/wounded and at X hospital. No other information was given. Sometimes the book the hospital kept was the source for the information on the service record card. If this is the case, much more information is then given on the card such as type of wound or sickness. It sounds like a muster roll was the source of information on your relative. Some hospital books exist and were carded all those years ago, but most did not survive to be carded into the service records. If you know the dates someone was in a particular hospital you could check the National Archives to see if they hold that hospitals books for a date range you are looking for. The clerks did miss individuals and information when they went throught the records and transcribed it onto the service cards. You may also want to check the Supplemental Service Records. They are said to have additional information on about 10% of all Confederate soldiers. They are in the Nat. Archives on microfilm. The Arkansas State archives also has a set, and should be able to search them quicker than the Nat. Archives. I think cost is $15. I hope this is of some help.