SOIUSA code is thecode used in theInternational Standardized Mountain Subdivision of the Alps (ISMSA or SOIUSA), a proposal by Italian Alpinist, Sergio Marazzi, to re-categorize themountains andmountain ranges of theAlps. The proposal has been aired since 2005 but has yet to receive official recognition.

SOIUSA divides theAlps in two main regions, theWestern Alps andEastern Alps.These two main regions are further divided in:

• 5 major sectors (SR);
• 36 sections (SZ);
• 132 subsections (STS);
• 333 supergroups (SPG);
• 870 groups (GR);
• 1625 subgroups (STG).

Using this system, any Alpinemountain can be given a code which shows which region, sector, section, subsection, supergroup, group and subgroup it belongs to.

SOIUSA code is built in the following way:

• 2 main parts:
  • Western Alps are identified byroman numeralI;
  • Eastern Alps are identified by roman numeralII;
• 5 major sectors:
  • inWestern Alps:
    • South-western Alps are identified by upper-case letterA;
    • North-western Alps are identified by upper-case letterB;
  • inEastern Alps:
    • Central Eastern Alps are identified by upper-case letterA;
    • Northern Limestone Alps are identified by upper-case letterB;
    • Southern Limestone Alps are identified by lower-case letterC;
• 36 sections: identified bynumbers from 1 to 36 starting fromLigurian Alps and ending withSlovenian prealps;
• 132 subsections: identified in their own section by theroman numerals needed to count every subsection;
• 333 supergroups: identified in their own subsection by all the upper-case letters needed to count every supergroup;
• 870 groups: identified in their own supergroup by all thenumbers needed to count every group;
• 1625 subgroups: identified in their own group by all the lower-case letters needed to count every subgroup.

Following these rules and using the punctuation marks (/;-;.;-;. and.) a summit will be encoded in the following way:

roman numeral (I or II)/upper-case letter (A, B or C)-number from 1 to 36.roman numeral-upper-case letter.number.lower-case letter

In some case the final lower-case letter can be missing because some group is not divided into subgroups.
It can seldom happen (i.e.:Monte Tagliaferro) that a subgroup too is further divided in sectors; in that case the last lower-case letter is followed by a slash (/) and a second lower-case letter.

Pointe Sommeiller (Fr) /Punta Sommeiller (It) code is:

I/A-4.III-B.6.b

It can be decoded in the following way:

• I: the mountain belongs toWestern Alps,
• A: the mountain belongs toSouth Western Alps,
• 4: the mountain belongs toCottian Alps,
• III: the mountain belongs toNorthern Cottian Alps (which are the third out of three subsections belonging to Cottian Alps),
• B: the mountain belongs tochaîne Bernaude-Pierre Menue-Ambin (Fr) /catena Bernauda-Pierre Menue-Ambin (It) (which is the second out of two supergroups belonging to Northern Cottian Alps),
• 6: the mountain belongs togroupe d'Ambin (Fr) /gruppo d'Ambin (It) (which is the sixth out of six groups belonging to Bernaude-Pierre Menue-Ambin supergroup),
• b: the mountain belongs to a subgroup calledcrête Sommeiller-Vallonetto (Fr) /sottogruppo Sommeiller-Vallonetto (It) (which is the second out of three subgroups belonging to Ambin group).

• Marazzi, Sergio (2005).Atlante Orografico delle Alpi. SOIUSA (in Italian). Priuli & Verlucca.ISBN 978-88-8068-273-8.

• Alps
• Encodings

• CS1 Italian-language sources (it)