diff --git a/R/dsl.R b/R/dsl.R
index 7064bd4a..30c6c8af 100644
--- a/R/dsl.R
+++ b/R/dsl.R
@@ -24,7 +24,7 @@
 ##'   function.
 ##'
 ##' @param fixed An optional list of values that can be used within
-##'   the dsl code.  Anything you provide here is available for your
+##'   the DSL code.  Anything you provide here is available for your
 ##'   calculations.  In the interest of future compatibility, we check
 ##'   currently that all elements are scalars.  In future this may
 ##'   become more flexible and allow passing environments, etc.  Once
diff --git a/man/monty_dsl.Rd b/man/monty_dsl.Rd
index 1040e636..7edd127b 100644
--- a/man/monty_dsl.Rd
+++ b/man/monty_dsl.Rd
@@ -28,7 +28,7 @@ then we will error if it is not possible to create a gradient
 function.}
 
 \item{fixed}{An optional list of values that can be used within
-the dsl code.  Anything you provide here is available for your
+the DSL code.  Anything you provide here is available for your
 calculations.  In the interest of future compatibility, we check
 currently that all elements are scalars.  In future this may
 become more flexible and allow passing environments, etc.  Once
diff --git a/vignettes/dsl.Rmd b/vignettes/dsl.Rmd
index d178ef18..4c77b693 100644
--- a/vignettes/dsl.Rmd
+++ b/vignettes/dsl.Rmd
@@ -67,3 +67,55 @@ The computed properties for the model are:
 ```{r}
 prior$properties
 ```
+
+# Calculations in the DSL
+
+Sometimes it will be useful to perform calculations in the code; you can do this with assignments.  Most trivially, giving names to numbers may help make code more understandable:
+
+```{r}
+m <- monty_dsl({
+  mu <- 10
+  sd <- 2
+  a ~ Normal(mu, sd)
+})
+```
+
+You can also use this to do things like:
+
+```{r}
+m <- monty_dsl({
+  a ~ Normal(0, 1)
+  b ~ Normal(0, 1)
+  mu <- (a + b) / 2
+  c ~ Normal(mu, 1)
+})
+```
+
+Where `c` is drawn from a normal distribution with a mean that is the average of `a` and `b`.
+
+# Pass in fixed data
+
+You can also pass in a list of data with values that should be available in the DSL code.  For example, our first example:
+
+```{r}
+prior <- monty_dsl({
+  alpha ~ Normal(178, 20)
+  beta ~ Normal(0, 10)
+  sigma ~ Uniform(0, 50)
+})
+```
+
+Might be written as
+
+```{r}
+fixed <- list(alpha_mean = 170, alpha_sd = 20,
+              beta_mean = 0, beta_sd = 10,
+              sigma_max = 50)
+prior <- monty_dsl({
+  alpha ~ Normal(alpha_mean, alpha_sd)
+  beta ~ Normal(beta_mean, beta_sd)
+  sigma ~ Uniform(0, sigma_max)
+}, fixed = fixed)
+```
+
+Values you pass in this way are **fixed** (hence the name!) and cannot be modified after the model object is created.