diff --git a/src/fontra/client/core/classes.json b/src/fontra/client/core/classes.json
index ef5436b18..5e465627c 100644
--- a/src/fontra/client/core/classes.json
+++ b/src/fontra/client/core/classes.json
@@ -18,6 +18,10 @@
     "axes": {
       "type": "list",
       "subtype": "GlobalAxis"
+    },
+    "sources": {
+      "type": "list",
+      "subtype": "GlobalSource"
     }
   },
   "VariableGlyph": {
@@ -66,6 +70,10 @@
       "type": "dict",
       "subtype": "float"
     },
+    "locationBase": {
+      "type": "str",
+      "optional": true
+    },
     "inactive": {
       "type": "bool"
     },
@@ -102,6 +110,14 @@
     "verticalOrigin": {
       "type": "float",
       "optional": true
+    },
+    "anchors": {
+      "type": "list",
+      "subtype": "Anchor"
+    },
+    "guidelines": {
+      "type": "list",
+      "subtype": "Guideline"
     }
   },
   "PackedPath": {
@@ -167,6 +183,40 @@
       "type": "float"
     }
   },
+  "Anchor": {
+    "name": {
+      "type": "str"
+    },
+    "x": {
+      "type": "float"
+    },
+    "y": {
+      "type": "float"
+    },
+    "customData": {
+      "type": "dict",
+      "subtype": "Any"
+    }
+  },
+  "Guideline": {
+    "name": {
+      "type": "str",
+      "optional": true
+    },
+    "x": {
+      "type": "float"
+    },
+    "y": {
+      "type": "float"
+    },
+    "angle": {
+      "type": "float"
+    },
+    "customData": {
+      "type": "dict",
+      "subtype": "Any"
+    }
+  },
   "GlobalAxis": {
     "name": {
       "type": "str"
@@ -193,5 +243,35 @@
     "hidden": {
       "type": "bool"
     }
+  },
+  "GlobalSource": {
+    "name": {
+      "type": "str"
+    },
+    "location": {
+      "type": "dict",
+      "subtype": "float"
+    },
+    "verticalMetrics": {
+      "type": "dict",
+      "subtype": "GlobalMetric"
+    },
+    "guidelines": {
+      "type": "list",
+      "subtype": "Guideline"
+    },
+    "customData": {
+      "type": "dict",
+      "subtype": "Any"
+    }
+  },
+  "GlobalMetric": {
+    "value": {
+      "type": "float"
+    },
+    "customData": {
+      "type": "dict",
+      "subtype": "Any"
+    }
   }
 }
diff --git a/src/fontra/core/classes.py b/src/fontra/core/classes.py
index 89cad5320..4e86393f6 100644
--- a/src/fontra/core/classes.py
+++ b/src/fontra/core/classes.py
@@ -10,45 +10,87 @@
 
 from .path import PackedPath, Path, Point, PointType
 
-Location = dict[str, float]
-CustomData = dict[str, Any]
+
+@dataclass(kw_only=True)
+class Font:
+    unitsPerEm: int = 1000
+    glyphs: dict[str, VariableGlyph] = field(default_factory=dict)
+    glyphMap: dict[str, list[int]] = field(default_factory=dict)
+    customData: CustomData = field(default_factory=dict)
+    axes: list[Union[GlobalAxis, GlobalDiscreteAxis]] = field(default_factory=list)
+    sources: list[GlobalSource] = field(default_factory=list)
+
+    def _trackAssignedAttributeNames(self):
+        # see fonthandler.py
+        self._assignedAttributeNames = set()
+
+    def __setattr__(self, attrName, value):
+        if hasattr(self, "_assignedAttributeNames"):
+            self._assignedAttributeNames.add(attrName)
+        super().__setattr__(attrName, value)
 
 
 @dataclass(kw_only=True)
-class Component:
+class GlobalSource:
     name: str
-    transformation: DecomposedTransform = field(default_factory=DecomposedTransform)
-    location: Location = field(default_factory=Location)
+    location: Location = field(default_factory=dict)
+    verticalMetrics: dict[str, GlobalMetric] = field(default_factory=dict)
+    guidelines: list[Union[Guideline, HorizontalGuideline, VerticalGuideline]] = field(
+        default_factory=list
+    )
+    customData: CustomData = field(default_factory=dict)
 
 
 @dataclass(kw_only=True)
-class StaticGlyph:
-    path: Union[PackedPath, Path] = field(default_factory=PackedPath)
-    components: list[Component] = field(default_factory=list)
-    xAdvance: Optional[float] = None
-    yAdvance: Optional[float] = None
-    verticalOrigin: Optional[float] = None
+class GlobalMetric:
+    value: float
+    customData: CustomData = field(default_factory=dict)
 
-    def convertToPackedPaths(self):
-        return replace(self, path=self.path.asPackedPath())
 
-    def convertToPaths(self):
-        return replace(self, path=self.path.asPath())
+@dataclass(kw_only=True)
+class Guideline:
+    name: Optional[str]
+    x: float
+    y: float
+    angle: float
+    customData: CustomData = field(default_factory=dict)
 
 
 @dataclass(kw_only=True)
-class Source:
-    name: str
-    layerName: str
-    location: Location = field(default_factory=Location)
-    inactive: bool = False
-    customData: CustomData = field(default_factory=CustomData)
+class HorizontalGuideline:
+    name: Optional[str]
+    y: float
+    customData: CustomData = field(default_factory=dict)
 
 
 @dataclass(kw_only=True)
-class Layer:
-    glyph: StaticGlyph
-    customData: CustomData = field(default_factory=CustomData)
+class VerticalGuideline:
+    name: str | None
+    x: float
+    customData: CustomData = field(default_factory=dict)
+
+
+@dataclass(kw_only=True)
+class GlobalAxis:
+    name: str  # this identifies the axis
+    label: str  # a user friendly label
+    tag: str  # the opentype 4-char tag
+    minValue: float
+    defaultValue: float
+    maxValue: float
+    mapping: list[list[float]] = field(default_factory=list)
+    hidden: bool = False
+
+
+@dataclass(kw_only=True)
+class GlobalDiscreteAxis:
+    name: str  # this identifies the axis
+    label: str  # a user friendly label
+    tag: str  # the opentype 4-char tag
+    values: list[float]
+    defaultValue: float
+    mapping: list[list[float]] = field(default_factory=list)
+    hidden: bool = False
 
 
 @dataclass(kw_only=True)
@@ -65,7 +107,7 @@ class VariableGlyph:
     axes: list[LocalAxis] = field(default_factory=list)
     sources: list[Source] = field(default_factory=list)
     layers: dict[str, Layer] = field(default_factory=dict)
-    customData: CustomData = field(default_factory=CustomData)
+    customData: CustomData = field(default_factory=dict)
 
     def convertToPackedPaths(self):
         return _convertToPathType(self, True)
@@ -74,11 +116,59 @@ def convertToPaths(self):
         return _convertToPathType(self, False)
 
 
-def _hasAnyPathType(varGlyph, pathType):
-    return any(
-        isinstance(layer.glyph.path, pathType) for layer in varGlyph.layers.values()
+@dataclass(kw_only=True)
+class Source:
+    name: str
+    layerName: str
+    location: Location = field(default_factory=dict)
+    locationBase: Optional[str] = None
+    inactive: bool = False
+    customData: CustomData = field(default_factory=dict)
+
+
+@dataclass(kw_only=True)
+class Layer:
+    glyph: StaticGlyph
+    customData: CustomData = field(default_factory=dict)
+
+
+@dataclass(kw_only=True)
+class StaticGlyph:
+    path: Union[PackedPath, Path] = field(default_factory=PackedPath)
+    components: list[Component] = field(default_factory=list)
+    xAdvance: Optional[float] = None
+    yAdvance: Optional[float] = None
+    verticalOrigin: Optional[float] = None
+    anchors: list[Anchor] = field(default_factory=list)
+    guidelines: list[Union[Guideline, HorizontalGuideline, VerticalGuideline]] = field(
+        default_factory=list
     )
 
+    def convertToPackedPaths(self):
+        return replace(self, path=self.path.asPackedPath())
+
+    def convertToPaths(self):
+        return replace(self, path=self.path.asPath())
+
+
+@dataclass(kw_only=True)
+class Component:
+    name: str
+    transformation: DecomposedTransform = field(default_factory=DecomposedTransform)
+    location: Location = field(default_factory=dict)
+
+
+@dataclass(kw_only=True)
+class Anchor:
+    name: str
+    x: float
+    y: float
+    customData: CustomData = field(default_factory=dict)
+
+
+Location = dict[str, float]
+CustomData = dict[str, Any]
+
 
 def _convertToPathType(varGlyph, packedPath):
     if not _hasAnyPathType(varGlyph, Path if packedPath else PackedPath):
@@ -97,49 +187,10 @@ def _convertToPathType(varGlyph, packedPath):
     )
 
 
-@dataclass(kw_only=True)
-class GlobalAxis:
-    name: str  # this identifies the axis
-    label: str  # a user friendly label
-    tag: str  # the opentype 4-char tag
-    minValue: float
-    defaultValue: float
-    maxValue: float
-    mapping: list[list[float]] = field(default_factory=list)
-    hidden: bool = False
-
-
-@dataclass(kw_only=True)
-class GlobalDiscreteAxis:
-    name: str  # this identifies the axis
-    label: str  # a user friendly label
-    tag: str  # the opentype 4-char tag
-    values: list[float]
-    defaultValue: float
-    mapping: list[list[float]] = field(default_factory=list)
-    hidden: bool = False
-
-
-GlyphSet = dict[str, VariableGlyph]
-GlyphMap = dict[str, list[int]]
-
-
-@dataclass(kw_only=True)
-class Font:
-    unitsPerEm: int = 1000
-    glyphs: GlyphSet = field(default_factory=GlyphSet)
-    glyphMap: GlyphMap = field(default_factory=GlyphMap)
-    customData: CustomData = field(default_factory=CustomData)
-    axes: list[Union[GlobalAxis, GlobalDiscreteAxis]] = field(default_factory=list)
-
-    def _trackAssignedAttributeNames(self):
-        # see fonthandler.py
-        self._assignedAttributeNames = set()
-
-    def __setattr__(self, attrName, value):
-        if hasattr(self, "_assignedAttributeNames"):
-            self._assignedAttributeNames.add(attrName)
-        super().__setattr__(attrName, value)
+def _hasAnyPathType(varGlyph, pathType):
+    return any(
+        isinstance(layer.glyph.path, pathType) for layer in varGlyph.layers.values()
+    )
 
 
 def makeSchema(*classes, schema=None):
diff --git a/test-common/fonts/MutatorSans.fontra/font-data.json b/test-common/fonts/MutatorSans.fontra/font-data.json
index 80631efbd..34f511d6a 100644
--- a/test-common/fonts/MutatorSans.fontra/font-data.json
+++ b/test-common/fonts/MutatorSans.fontra/font-data.json
@@ -43,5 +43,6 @@
 "mapping": [],
 "hidden": false
 }
-]
+],
+"sources": []
 }