diff --git a/kiwi_simple_metrics/settings/metric.py b/kiwi_simple_metrics/settings/metric.py
index 90a7fee..14a3722 100644
--- a/kiwi_simple_metrics/settings/metric.py
+++ b/kiwi_simple_metrics/settings/metric.py
@@ -2,7 +2,7 @@ import math
 from typing import Any, Literal
 
 from pydantic import (BaseModel, DirectoryPath, Field, FieldValidationInfo,
-                      field_validator)
+                      FilePath, field_validator)
 
 
 class MetricSettings(BaseModel):
@@ -81,6 +81,40 @@ class DiskMS(MetricSettings):
     paths: list[DirectoryPath] = Field(default_factory=list)
 
 
-class ScriptMS(MetricSettings):
-    name: str = "External Script"
+class ExternalMS(MetricSettings):
+    """
+    External Metric
+    =====
+
+    This metric's values are defined external executables (e.g. bash scripts).
+    Any executable with suitable output can be used as a value for this metric.
+
+    To comply, the executable's output must start with four consecutive lines,
+    holding the following information:
+
+    1. value name (max. 100 characters)
+    2. percent threshold
+    3. the string "normal" or "inverted", without quotes
+    4. percent current value
+
+    Percentages may be floating point numbers and must use a decimal point "."
+    as a separator in that case.
+
+    Non-compliance will be reported as failed values as follows:
+
+    - non-executable files are reported as the files' basename
+    - executables with generally noncompliant outputs are reported as
+      the first line of their output truncated to 100 chars
+    - failure to parse the threshold or inversion results in
+      an upper threshold of 0%
+    - failure to parse the current value results in
+      an upper threshold of 0% and a value of 100%
+    - compliant executables with non-zero exit status are still
+      reported as a failed value
+    """
+
+    name: str = "External Metrics"
     threshold: float = 0
+
+    # path to executable files
+    executables: list[FilePath] = Field(default_factory=list)