| v_ | Local variables declared within a function or procedure |
| c_ | Cursor |
| r_ | Record variable for CURSOR FOR loops |
| gv_ | Global variables declared within a package |
| gl_ | Global constants declared within a package |
| gc_ | Global cursors declared within a package |
| _yn | Pseudo-Boolean items using 'Y'and 'N'for values |
| _cd | Variables restricted to a set of "codes" |
| _tx | All other text formats not covered by cd or yn |
| _id, _oid | Variables to store unique IDs / object IDs |
| _nr | Any numeric datatype not covered by _id or _oid |
| _dt | Date |
| _ts | Timestamp datatype |
| _tf | Boolean variable (TRUE/FALSE values) |
| _rec | Record defined via %ROWTYPE reference to existing table/view/cursor |
| _ref | REF CURSOR defined via SYS_REFCURSOR datatype |
| _cl | CLOB datatype |
| _bl | BLOB datatype |
| _bf | BFILE datatype |