JD Edwards EnterpriseOne APIs data types

Hello community

Actually I am trying to  building  a C business function to use it on JD Edwards EnterpriseOne, but I could not find  documentation about data types that can be used or exist on JD Edwards EnterpriseOne.

Does anybody of you have information about this topic?.

I have this example of variable declaration and I would like to know if the data types that appear at the following example are of JD Edwards E1 APIs or   by C language itself.

   ID idRtnVal = ER_SUCCESS;

  JCHAR evt_cCodigoMantenimiento_AA01 = 0;

  JCHAR evt_cCodigoMensaje_AA01 = 0;

  JCHAR evt_szUserId_USER[11] = { 0 };

  JCHAR evt_szProgramId_PID[11] = { 0 };