igs: create identifiers.md

igs/identifiers.md

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+# IGS identifiers
+
+### Variables and values
+
+The following variables are used across the different identifiers and can denote the listed values:
+
+* `$v`: Game version
+  * For example, `100` refers to version 1.00
+  * Another example, `202` refers to version 2.02
+* `$d`: Destination, target locale/market/region
+  * `CN`: China
+  * `FA`: Export
+  * `JA`: Japan
+  * `US`: US
+  * `CNC`
+  * `SAE`
+
+## Identifiers
+
+### Version identifier
+
+[Packages](versions.md) that can be acquired, e.g. bought or leased.
+
+* Format: `M-$v$d`
+* Example: [M-100CN] (version 1.00, Chinese region)