This field specifies how any carrier code ($CC) together with the first
group ($FG) in the national significant number should be formatted
when formatWithCarrierCode is called, if carrier codes are used for a
certain country.
format specifies how the national (significant) number matched by
pattern should be formatted.
Using the same example as above, format could contain "$1 $2 $3",
meaning that the number should be formatted as "20 7031 3000".
Each $x are replaced by the numbers captured by group x in the
regex specified by pattern.
This field is a regex that is used to match a certain number of digits
at the beginning of the national (significant) number. When the match is
successful, the accompanying pattern and format should be used to format
this number. For example, if leading_digits="1-3|44", then all the
national numbers starting with 1, 2, 3 or 44 should be formatted using the
accompanying pattern and format.
This field specifies how the national prefix ($NP) together with the first
group ($FG) in the national significant number should be formatted in
the NATIONAL format when a national prefix exists for a certain country.
For example, when this field contains "($NP$FG)", a number from Beijing,
China (whose $NP = 0), which would by default be formatted without
national prefix as 10 1234 5678 in NATIONAL format, will instead be
formatted as (010) 1234 5678; to format it as (0)10 1234 5678, the field
would contain "($NP)$FG". Note $FG should always be present in this field,
but $NP can be omitted. For example, having "$FG" could indicate the
number should be formatted in NATIONAL format without the national prefix.
This is commonly used to override the rule specified for the territory in
the XML file.
This field specifies whether the $NP can be omitted when formatting a
number in national format, even though it usually wouldn't be. For example,
a UK number would be formatted by our library as 020 XXXX XXXX. If we have
commonly seen this number written by people without the leading 0, for
example as (20) XXXX XXXX, this field would be set to true. This will be
inherited from the value set for the territory in the XML file, unless a
national_prefix_optional_when_formatting is defined specifically for this
NumberFormat.
pattern is a regex that is used to match the national (significant)
number. For example, the pattern "(20)(\d{4})(\d{4})" will match number
"2070313000", which is the national (significant) number for Google London.
Note the presence of the parentheses, which are capturing groups what
specifies the grouping of numbers.
