| RDB$FUNCTION_NAME
 | CHAR(63)
 | The unique name (declared identifier) of the function | 
| RDB$ARGUMENT_POSITION
 | SMALLINT
 | The position of the argument in the list of arguments | 
| RDB$MECHANISM
 | SMALLINT
 | Flag: how this argument is passed: 0- by value
 1- by reference
 2- by descriptor
 3- by BLOB descriptor
 4- by scalar array
 5- by reference with null
 Only for legacy external functions. | 
| RDB$FIELD_TYPE
 | SMALLINT
 | Data type code defined for the column: 7-SMALLINT
 8-INTEGER
 10-FLOAT
 12-DATE
 13-TIME
 14-CHAR
 16-BIGINT
 23-BOOLEAN
 24-DECFLOAT(16)
 25-DECFLOAT(34)
 26-INT128
 27-DOUBLE PRECISION
 28-TIME WITH TIME ZONE
 29-TIMESTAMP WITH TIME ZONE
 35-TIMESTAMP
 37-VARCHAR
 40-CSTRING(null-terminated text)
 45-BLOB_ID
 261-BLOB
 Only for legacy external functions. | 
| RDB$FIELD_SCALE
 | SMALLINT
 | The scale of an integer or a fixed-point argument.It is an exponent of 10. Only for legacy external functions. | 
| RDB$FIELD_LENGTH
 | SMALLINT
 | Argument length in bytes: BOOLEAN= 1
 SMALLINT= 2
 INTEGER= 4
 DATE= 4
 TIME= 4
 BIGINT= 8
 DECFLOAT(16)= 8
 DOUBLE PRECISION= 8
 TIMESTAMP= 8
 TIME WITH TIME ZONE= 8
 BLOB_ID= 8
 TIMESTAMP WITH TIME ZONE= 12
 INT128= 16
 DECFLOAT(34)= 16
 Only for legacy external functions. | 
| RDB$FIELD_SUB_TYPE
 | SMALLINT
 | Stores the BLOBsubtype for an argument of aBLOBdata type. Only for legacy external functions. | 
| RDB$CHARACTER_SET_ID
 | SMALLINT
 | The identifier of the character set for a character argument. Only for legacy external functions. | 
| RDB$FIELD_PRECISION
 | SMALLINT
 | The number of digits of precision available for the data type of the argument. Only for legacy external functions. | 
| RDB$CHARACTER_LENGTH
 | SMALLINT
 | The length of a CHARorVARCHARargument in characters (not in bytes). Only for legacy external functions. | 
| RDB$PACKAGE_NAME
 | CHAR(63)
 | Package name of the function (or NULLfor a top-level function) | 
| RDB$ARGUMENT_NAME
 | CHAR(63)
 | Parameter name | 
| RDB$FIELD_SOURCE
 | CHAR(63)
 | The name of the user-created domain, when a domain is referenced instead of a data type.If the name starts with the prefix “RDB$”, it is the name of the domain automatically generated by the system for the parameter. | 
| RDB$DEFAULT_VALUE
 | BLOB BLR
 | The binary language representation (BLR) of the default value of the parameter | 
| RDB$DEFAULT_SOURCE
 | BLOB TEXT
 | The default value for the parameter, in PSQL code | 
| RDB$COLLATION_ID
 | SMALLINT
 | The identifier of the collation used for a character parameter | 
| RDB$NULL_FLAG
 | SMALLINT
 | The flag indicating whether NULLis allowable | 
| RDB$ARGUMENT_MECHANISM
 | SMALLINT
 | Parameter passing mechanism for non-legacy functions: 0- by value
 1- by reference
 2- through a descriptor
 3- via the BLOB descriptor
 | 
| RDB$FIELD_NAME
 | CHAR(63)
 | The name of the column the parameter references, if it was declared using TYPE OF COLUMNinstead of a regular data type.Used in conjunction withRDB$RELATION_NAME(see next). | 
| RDB$RELATION_NAME
 | CHAR(63)
 | The name of the table the parameter references, if it was declared using TYPE OF COLUMNinstead of a regular data type | 
| RDB$SYSTEM_FLAG
 | SMALLINT
 | Flag: 0- user-defined
 1or higher - system-defined
 | 
| RDB$DESCRIPTION
 | BLOB TEXT
 | Optional description of the function argument (comment) |