diff --git a/schemas/api-config/field.json b/schemas/api-config/field.json
index 359cc5f..8f30af2 100644
--- a/schemas/api-config/field.json
+++ b/schemas/api-config/field.json
@@ -85,34 +85,68 @@
                     ]
                 },
                 "choices": {
-                    "type": "array",
-                    "description": "choices to select from",
-                    "items": {
-                        "type": "object",
-                        "properties": {
-                            "id": {
-                                "oneOf": [
-                                    {
-                                        "type": "null"
-                                    },
-                                    {
-                                        "type": "string"
-                                    },
-                                    {
-                                        "type": "number"
+                    "oneOf": [
+                        {
+                            "type": "object",
+                            "description": "endpoint configuration",
+                            "additionalProperties": false,
+                            "properties": {
+                                "endpoint": {
+                                    "type": "string",
+                                    "description": "endpoint URL or path"
+                                },
+                                "params": {
+                                    "type": "object",
+                                    "description": "query parameters"
+                                },
+                                "mapping": {
+                                    "type": "object",
+                                    "description": "data mapping",
+                                    "additionalProperties": false,
+                                    "properties": {
+                                        "id": {
+                                            "type": "string",
+                                            "description": "name of id field"
+                                        },
+                                        "name": {
+                                            "type": "string",
+                                            "description": "name of name/description field"
+                                        }
                                     }
-                                ]
-                            },
-                            "name": {
-                                "description": "name is human readable value",
-                                "$ref": "#/definitions/i18nString"
-                            },
-                            "chipStyle": {
-                                "$ref": "https://raw.githubusercontent.com/rcorp/css-schema/master/schema.json"
+                                }
                             }
                         },
-                        "required": ["id", "name"]
-                    }
+                        {
+                            "type": "array",
+                            "description": "choices to select from",
+                            "items": {
+                                "type": "object",
+                                "properties": {
+                                    "id": {
+                                        "oneOf": [
+                                            {
+                                                "type": "null"
+                                            },
+                                            {
+                                                "type": "string"
+                                            },
+                                            {
+                                                "type": "number"
+                                            }
+                                        ]
+                                    },
+                                    "name": {
+                                        "description": "name is human readable value",
+                                        "$ref": "#/definitions/i18nString"
+                                    },
+                                    "chipStyle": {
+                                        "$ref": "https://raw.githubusercontent.com/rcorp/css-schema/master/schema.json"
+                                    }
+                                },
+                                "required": ["id", "name"]
+                            }
+                        }
+                    ]
                 },
                 "valueMap": {
                     "type": "object",