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$FIELD_SUB_TYPE
  | 
SMALLINT
  | 
Stores the BLOB subtype for an argument of a BLOB data type. 
Only for legacy external functions.  | 
RDB$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 CHAR or VARCHAR argument in characters (not in bytes). 
Only for legacy external functions.  | 
RDB$PACKAGE_NAME
  | 
CHAR(63)
  | 
Package name of the function (or NULL for a top-level function)  | 
RDB$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 NULL is 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 COLUMN instead of a regular data type.Used in conjunction with RDB$RELATION_NAME (see next).  | 
RDB$RELATION_NAME
  | 
CHAR(63)
  | 
The name of the table the parameter references, if it was declared using TYPE OF COLUMN instead of a regular data type  | 
RDB$SYSTEM_FLAG
  | 
SMALLINT
  | 
Flag: 
0 - user-defined
 1 or higher - system-defined
  | 
RDB$DESCRIPTION
  | 
BLOB TEXT
  | 
Optional description of the function argument (comment)  |