diff --git a/schema/5.1.0/schema.md b/schema/5.1.0/schema.md
index 198cd403..2f55f4a7 100644
--- a/schema/5.1.0/schema.md
+++ b/schema/5.1.0/schema.md
@@ -367,6 +367,7 @@ Curators MUST annotate the following columns in the `obs` dataframe:
           <li>
             the most accurate descendant of <a href="https://www.ebi.ac.uk/ols4/ontologies/efo/classes?obo_id=EFO%3A0010183"><code>"EFO:0010183"</code></a>  for <i>single cell library construction</i>
           </li></ul>
+        If <code>assay_ontology_term_id</code> is either <a href="https://www.ebi.ac.uk/ols4/ontologies/efo/classes?obo_id=EFO%3A0010961"><code>"EFO:0010961"</code></a> for <i>Visium Spatial Gene Expression</i> or <a href="https://www.ebi.ac.uk/ols4/ontologies/efo/classes?obo_id=EFO%3A0030062"><code>"EFO:0030062"</code></a> for <i>Slide-seqV2</i>. then all observations MUST contain the same value.<br><br>
         An assay based on 10X Genomics products SHOULD either be <a href="https://www.ebi.ac.uk/ols4/ontologies/efo/classes?obo_id=EFO%3A0008995"><code>"EFO:0008995"</code></a> for <i>10x technology</i> or <b>preferably</b> its most accurate descendant. An assay based on <i>SMART (Switching Mechanism at the 5' end of the RNA Template) or SMARTer technology</i> SHOULD either be <a href="https://www.ebi.ac.uk/ols4/ontologies/efo/classes?obo_id=EFO%3A0010184"><code>"EFO:0010184"</code></a> for <i>Smart-like</i> or preferably its most accurate descendant.<br><br>
        <br>Recommended values for specific assays:
           <br><br>
@@ -1872,6 +1873,7 @@ When a dataset is uploaded, CELLxGENE Discover MUST automatically add the `schem
 * obs (Cell metadata)
   * Added `array_col` for _Visium Spatial Gene Expression_ when <code>uns['spatial']['is_single']</code> is <code>True</code>
   * Added `array_row` for _Visium Spatial Gene Expression_ when <code>uns['spatial']['is_single']</code> is <code>True</code>
+  * Updated the requirements for `assay_ontology_term_id` for _Visium Spatial Gene Expression_ and _Slide-seqV2_. All observations must contain the same value.
   * Updated the requirements for `cell_type_ontology_term_id` for _Visium Spatial Gene Expression_ when <code>uns['spatial']['is_single']</code> is <code>True</code>. The value must be `"unknown"` if the corresponding value of `in_tissue` is `0`.
   * Added `in_tissue` for _Visium Spatial Gene Expression_ when <code>uns['spatial']['is_single']</code> is <code>True</code>
   * Updated the requirements for `is_primary_data` for _Visium Spatial Gene Expression_. The value must be <code>False</code>when <code>uns['spatial']['is_single']</code> is <code>False</code>.