Development tools : Web services tooling : Reference : Default dataname mapping rule
  
Default dataname mapping rule
The default rule of Dataname mapping is to convert an XML name into camel case style. It changes the first character of every word composing an XML name to uppercase, and the others to lowercase.
Example after applying the Camelcase Rule
 
Before conversion
After conversion
FIRST_NAME
firstName
SECONDName
secondName
SSNCode
ssnCode
So if you define the Global Data Dictionary, you should define firstName, secondName, ssnCode.
However, the Camel case Rule has the following limitations:
A_B_C --> abc (according to the rule, it should be aBC)
abc1Abc2e --> abc1Abc2E (according to the rule, it should be abc1Abc2e)
So if you define the Global Data Dictionary, you should define abc, abc1Abc2E other than aBC and abc1Abc2e
See also
Reference