Add Belgian OGM-VCS

docs/index.rst

@@ -130,6 +130,7 @@ Available formats
    be.eid
    be.iban
    be.nn
+   be.ogm_vcs
    be.ssn
    be.vat
    bg.egn

docs/stdnum.be.ogm_vcs.rst

@@ -0,0 +1,5 @@
+stdnum.be.ogm_vcs
+=================
+
+.. automodule:: stdnum.be.ogm_vcs
+   :members:

stdnum/be/ogm_vcs.py

@@ -0,0 +1,102 @@
+# ogm_vcs.py - functions for handling Belgian OGM-VCS
+# coding: utf-8
+#
+# Copyright (C) 2025 Cédric Krier
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
+"""Belgian OGM-VCS.
+
+The OGM-VCS is used in bank transfer as structured communication.
+
+* https://febelfin.be/en/publications/2023/febelfin-banking-standards-for-online-banking
+
+>>> compact('+++010/8068/17183+++')
+'010806817183'
+>>> validate('+++010/8068/17183+++')
+'010806817183'
+>>> validate('foo')
+Traceback (most recent call last):
+    ...
+InvalidFormat: ...
+>>> validate('010/8068/1718')
+Traceback (most recent call last):
+    ...
+InvalidLength: ...
+>>> validate('010/8068/17180')
+Traceback (most recent call last):
+    ...
+InvalidChecksum: ...
+>>> is_valid('010/8068/17183')
+True
+>>> is_valid('010/8068/17180')
+False
+>>> format('010806817183')
+'010/8068/17183'
+>>> checksum('0108068171')
+83
+>>> calc_check_digit('0108068171')
+'83'
+"""
+
+from __future__ import annotations
+
+from stdnum.exceptions import (
+    InvalidChecksum, InvalidFormat, InvalidLength, ValidationError)
+from stdnum.util import clean, isdigits
+
+
+def compact(number: str) -> str:
+    """Convert the number to the minimal representation. This strips the number
+    of any invalid separators and removes surrounding whitespace."""
+    return clean(number, ' +/').strip()
+
+
+def checksum(number: str) -> int:
+    """Calculate the checksum."""
+    return (int(number) % 97) or 97
+
+
+def calc_check_digit(number: str) -> str:
+    """Calculate the check digit that should be added."""
+    return '%02d' % checksum(number)
+
+
+def validate(number: str) -> str:
+    """Check if the number is a valid OGM-VCS."""
+    number = compact(number)
+    if not isdigits(number) or int(number) <= 0:
+        raise InvalidFormat()
+    if len(number) != 12:
+        raise InvalidLength()
+    if checksum(number[:-2]) != int(number[-2:]):
+        raise InvalidChecksum()
+    return number
+
+
+def is_valid(number: str) -> bool:
+    """Check if the number is a valid VAT number."""
+    try:
+        return bool(validate(number))
+    except ValidationError:
+        return False
+
+
+def format(number: str) -> str:
+    """Format the number provided for output."""
+    number = compact(number)
+    number = number.rjust(12, '0')
+    return f'{number[:3]}/{number[3:7]}/{number[7:]}'