diff --git a/au.org.access-nri/model/spack/environment/deployment/2-0-0.json b/au.org.access-nri/model/spack/environment/deployment/2-0-0.json
new file mode 100644
index 0000000..609f0ce
--- /dev/null
+++ b/au.org.access-nri/model/spack/environment/deployment/2-0-0.json
@@ -0,0 +1,183 @@
+{
+    "$id": "https://raw.githubusercontent.com/ACCESS-NRI/schema/main/au.org.access-nri/model/spack/environment/deployment/2-0-0.json",
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "title": "Restricted spack environment file schema for ACCESS-NRI continuous deployment",
+    "description": "This schema was adapted from https://github.com/ACCESS-NRI/spack/blob/releases/v0.21/lib/spack/spack/schema/env.py to specify a restricted form of spack.yaml to design generic deployment infrastructure.",
+    "type": "object",
+    "additionalProperties": false,
+    "properties": {
+      "spack": {
+        "type": "object",
+        "default": {},
+        "additionalProperties": true,
+        "properties": {
+          "packages": {
+            "type": "object",
+            "default": {},
+            "additionalProperties": true,
+            "properties": {
+              "gcc-runtime": {
+                "type": "object",
+                "default": {},
+                "additionalProperties": true,
+                "properties": {
+                  "require": {
+                    "type": "array",
+                    "minItems": 1,
+                    "additionalItems": true,
+                    "items": {
+                      "oneOf": [
+                        {
+                          "type": "object"
+                        },
+                        {
+                          "type": "string"
+                        }
+                      ]
+                    }
+                  }
+                }
+              }
+            },
+            "patternProperties": {
+              "(?!^(all|gcc-runtime)$)(^\\w[\\w-]*)": {
+                "type": "object",
+                "default": {},
+                "additionalProperties": true,
+                "properties": {
+                  "require": {
+                    "type": "array",
+                    "minItems": 1,
+                    "additionalItems": true,
+                    "items": [
+                      {
+                        "type": "string",
+                        "pattern": "^@[A-Za-z0-9.\\-_=\/]+$"
+                      },
+                      {
+                        "oneOf": [
+                          {
+                            "type": "object"
+                          },
+                          {
+                            "type": "string"
+                          }
+                        ]
+                      }
+                    ]
+                  }
+                }
+              }
+            }
+          },
+          "specs": {
+            "type": "array",
+            "default": [],
+            "minItems": 1,
+            "items": {
+              "type": "string"
+            }
+          },
+          "definitions": {
+            "type": "array",
+            "default": [],
+            "items": {
+              "type": "object",
+              "required": ["_name", "_version"],
+              "properties": {
+                "_name": {
+                  "type": "array",
+                  "minItems": 1,
+                  "maxItems": 1,
+                  "items": {
+                    "type": "string"
+                  }
+                },
+                "_version": {
+                  "type": "array",
+                  "minItems": 1,
+                  "maxItems": 1,
+                  "items": {
+                    "type": "string"
+                  }
+                },
+                "ROOT_PACKAGE": {
+                  "type": "array",
+                  "minItems": 1,
+                  "maxItems": 1,
+                  "items": {
+                    "type": "string"
+                  }
+                },
+                "ROOT_SPEC": {
+                  "type": "array",
+                  "items": {
+                    "type":"object",
+                    "properties": {
+                      "matrix": {
+                        "type": "array",
+                        "items": {
+                          "type": "array",
+                          "items": {
+                            "type": "string"
+                          }
+                        }
+                      },
+                      "exclude": {
+                        "type": "array",
+                        "items": {
+                          "type": "string"
+                        }
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "if": {
+      "properties": {
+        "spack": {
+          "type": "object",
+          "properties": {
+            "specs": {
+              "type": "array",
+              "contains": {
+                "const": "$ROOT_SPEC"
+              }
+            }
+          }
+        }
+      }
+    },
+    "then": {
+      "properties": {
+        "spack": {
+          "type": "object",
+          "properties": {
+            "definitions": {
+              "allOf": [
+                {
+                  "type": "array",
+                  "contains": {
+                    "type": "object",
+                    "required": ["ROOT_SPEC"]
+                  }
+                },
+                {
+                  "type": "array",
+                  "contains": {
+                    "type": "object",
+                    "required": ["ROOT_PACKAGE"]
+                  }
+                }
+              ]
+            }
+          }
+        }
+      }
+    }
+  }
diff --git a/au.org.access-nri/model/spack/environment/deployment/CHANGELOG.md b/au.org.access-nri/model/spack/environment/deployment/CHANGELOG.md
index 9933074..f992f52 100644
--- a/au.org.access-nri/model/spack/environment/deployment/CHANGELOG.md
+++ b/au.org.access-nri/model/spack/environment/deployment/CHANGELOG.md
@@ -1,5 +1,10 @@
 # `spack.yaml` Schema Changelog
 
+## 2-0-0
+
+* Require reserved definitions for `spack.definitions[]._name` and `spack.definitions[]._version`
+* Relax requirements on `spack.specs` entirely
+
 ## 1-0-7
 
 * Allow the use of `@latest` in `spack.specs[0]`. This is allowed for Prereleases, but not for Releases. This keeps continuity with local builds which can't use not-yet-existing `@git.TAG`s like Prerelease builds can.