is a character literal that describes the format of datetime or numeric data stored in a character string.
A format model does not change the internal representation of the value in the database.
When you convert a character string into a date or number, a format model determines how Oracle Database interprets the string.
The values of some formats are determined by the value of initialization parameters.
For such formats, you can specify the characters returned by these format elements implicitly using the initialization parameter All number format models cause the number to be rounded to the specified number of significant digits.
If a value has more significant digits to the left of the decimal place than are specified in the format, then pound signs (#) replace the value.
This event typically occurs when you are using A number format model is composed of one or more number format elements.
The tables that follow list the elements of a number format model and provide some examples.
Negative return values automatically contain a leading negative sign and positive values automatically contain a leading space unless the format model contains the Returns value with the specified number of digits with a leading space if positive or with a leading minus if negative.
Leading zeros are blank, except for a zero value, which returns a zero for the integer part of the fixed-point number.
Returns negative value with a leading minus sign (-).
Returns positive value with a leading plus sign (+).
Returns negative value with a trailing minus sign (-).
Returns positive value with a trailing plus sign (+).