diff --git a/src/field.rs b/src/field.rs
index 201b92e..ea9b669 100644
--- a/src/field.rs
+++ b/src/field.rs
@@ -12,6 +12,9 @@ pub struct Field {
     /// Specify the address increment, in Bytes, between two neighboring array members in the address map.
     #[serde(default, deserialize_with = "deserialize_int_opt")]
     pub dim_increment: Option<u32>,
+    /// Define the indices to use, if not numeric.  Comma separated (e.g. `A,B`).
+    #[serde(default)]
+    pub dim_index: Option<String>,
     /// Name string used to identify the field.
     pub name: String,
     /// String describing the details of the register.
@@ -53,6 +56,10 @@ impl DimGroup for Field {
         self.dim.and_then(|dim| self.dim_increment.map(|dim_increment| (dim, dim_increment)))
     }
 
+    fn dim_index(&self) -> &Option<String> {
+        &self.dim_index
+    }
+
     fn name(&self) -> &String {
         &self.name
     }
diff --git a/src/lib.rs b/src/lib.rs
index 5f5dd6e..a67292b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -88,13 +88,27 @@ pub fn rerun_if_env_changed() {
 pub(crate) trait DimGroup {
     fn dim(&self) -> Option<(u32, u32)>;
 
+    fn dim_index(&self) -> &Option<String>;
+
     fn name(&self) -> &String;
 
     fn dim_group(&self) -> Vec<(String, u32)> {
         if let Some((count, step)) = self.dim() {
             if count > 1 {
-                return (0..count)
-                    .map(|i| (self.name().replace("[%s]", &format!("_{}", i)), i * step))
+                let indices = self
+                    .dim_index()
+                    .as_ref()
+                    .map(|idx| idx.split(',').into_iter().map(|s| s.to_owned()).collect::<Vec<_>>())
+                    .unwrap_or_else(|| (0..count).map(|i| format!("{}", i)).collect::<Vec<_>>());
+                return indices
+                    .into_iter()
+                    .enumerate()
+                    .map(|(i, idx)| {
+                        (
+                            self.name().replace("[%s]", &format!("_{}", idx)).replace("%s", &idx),
+                            i as u32 * step,
+                        )
+                    })
                     .collect();
             }
         }
diff --git a/src/peripheral.rs b/src/peripheral.rs
index 0272d24..43262d3 100644
--- a/src/peripheral.rs
+++ b/src/peripheral.rs
@@ -28,6 +28,9 @@ pub struct Peripheral {
     /// Specify the address increment, in Bytes, between two neighboring array members in the address map.
     #[serde(default, deserialize_with = "deserialize_int_opt")]
     pub dim_increment: Option<u32>,
+    /// Define the indices to use, if not numeric.  Comma separated (e.g. `A,B`).
+    #[serde(default)]
+    pub dim_index: Option<String>,
     /// The string identifies the peripheral.
     pub name: String,
     /// The string provides an overview of the purpose and functionality of the peripheral.
@@ -310,6 +313,10 @@ impl DimGroup for Peripheral {
         self.dim.and_then(|dim| self.dim_increment.map(|dim_increment| (dim, dim_increment)))
     }
 
+    fn dim_index(&self) -> &Option<String> {
+        &self.dim_index
+    }
+
     fn name(&self) -> &String {
         &self.name
     }
diff --git a/src/register.rs b/src/register.rs
index 93ef1dc..3b9d5f5 100644
--- a/src/register.rs
+++ b/src/register.rs
@@ -20,6 +20,9 @@ pub struct Cluster {
     /// Specify the address increment, in Bytes, between two neighboring array members in the address map.
     #[serde(default, deserialize_with = "deserialize_int_opt")]
     pub dim_increment: Option<u32>,
+    /// Define the indices to use, if not numeric.  Comma separated (e.g. `A,B`).
+    #[serde(default)]
+    pub dim_index: Option<String>,
     /// String to identify the cluster.
     pub name: String,
     /// String describing the details of the register cluster.
@@ -44,6 +47,9 @@ pub struct Register {
     /// Specify the address increment, in Bytes, between two neighboring array members in the address map.
     #[serde(default, deserialize_with = "deserialize_int_opt")]
     pub dim_increment: Option<u32>,
+    /// Define the indices to use, if not numeric.  Comma separated (e.g. `A,B`).
+    #[serde(default)]
+    pub dim_index: Option<String>,
     /// String to identify the register.
     pub name: String,
     /// String describing the details of the register.
@@ -202,6 +208,10 @@ impl DimGroup for Cluster {
         self.dim.and_then(|dim| self.dim_increment.map(|dim_increment| (dim, dim_increment)))
     }
 
+    fn dim_index(&self) -> &Option<String> {
+        &self.dim_index
+    }
+
     fn name(&self) -> &String {
         &self.name
     }
@@ -212,6 +222,10 @@ impl DimGroup for Register {
         self.dim.and_then(|dim| self.dim_increment.map(|dim_increment| (dim, dim_increment)))
     }
 
+    fn dim_index(&self) -> &Option<String> {
+        &self.dim_index
+    }
+
     fn name(&self) -> &String {
         &self.name
     }