diff --git a/sdrf_pipelines/sdrf/sdrf_schema.py b/sdrf_pipelines/sdrf/sdrf_schema.py
index 4ac8be85..2c3cf8bf 100644
--- a/sdrf_pipelines/sdrf/sdrf_schema.py
+++ b/sdrf_pipelines/sdrf/sdrf_schema.py
@@ -56,7 +56,12 @@ def ontology_term_parser(cell_value: str = None):
     else:
         for name in values:
             value_terms = name.split("=")
-            term[value_terms[0].strip().upper()] = value_terms[1].strip().lower()
+            if len(value_terms) == 2:
+                term[value_terms[0].strip().upper()] = value_terms[1].strip().lower()
+            else:
+                raise ValueError(
+                    f"Invalid term: {name} after splitting by '=', please check the prefix (e.g. AC, NT, " f"TA..)"
+                )
     return term
 
 
@@ -109,8 +114,8 @@ def default_message(self):
     @staticmethod
     def validate_ontology_terms(cell_value, labels):
         """
-        Check if a cell value is in a list of labels or list of strings
-        :param cell_value: string line in cell
+        Check if a cell value is in a list of labels or list of string
+        :param cell_value: line in a cell
         :param labels: list of labels
         :return:
         """
@@ -124,7 +129,7 @@ def validate(self, series: pd.Series) -> pd.Series:
         """
         Validate if the term is present in the provided ontology. This method looks in the provided
         ontology _ontology_name
-        :param series: return the series that do not match the criteria
+        :param series: return series that do not match the criteria
         :return:
         """
         terms = [ontology_term_parser(x) for x in series.unique()]
@@ -165,7 +170,7 @@ def __new__(cls, ordered: bool = False, min_columns: int = 0) -> Any:
     def validate(self, panda_sdrf: sdrf = None) -> typing.List[LogicError]:
         errors = []
 
-        # Check minimum number of columns
+        # Check the minimum number of columns
         if check_minimum_columns(panda_sdrf, self._min_columns):
             error_message = (
                 "The number of columns in the SDRF ({}) is smaller than the number of mandatory fields ({})".format(
@@ -179,7 +184,7 @@ def validate(self, panda_sdrf: sdrf = None) -> typing.List[LogicError]:
         if error_mandatory is not None:
             errors.append(error_mandatory)
 
-        # Check the columns order
+        # Check the column order
         error_columns_order = self.validate_columns_order(panda_sdrf)
         if error_columns_order is not None:
             errors.extend(error_columns_order)
diff --git a/sdrf_pipelines/zooma/ols.py b/sdrf_pipelines/zooma/ols.py
index ec2197d6..c06084ab 100644
--- a/sdrf_pipelines/zooma/ols.py
+++ b/sdrf_pipelines/zooma/ols.py
@@ -16,7 +16,7 @@
 
 import requests
 
-OLS = "https://www.ebi.ac.uk/ols"
+OLS = "https://www.ebi.ac.uk/ols4"
 
 __all__ = ["OlsClient"]
 
@@ -45,7 +45,7 @@ def _concat_str_or_list(input_str):
 def _dparse(iri):
     """
     Double url encode the IRI, which is required
-    @:param iri IRI in the OLS
+    @:param iri in the OLS
     """
     return urllib.parse.quote_plus(urllib.parse.quote_plus(iri))
 
@@ -70,7 +70,7 @@ def __init__(self, ols_base=None, ontology=None, field_list=None, query_fields=N
 
     def besthit(self, name, **kwargs):
         """
-        select first element of the /search API response
+        select a first element of the /search API response
         """
         search_resp = self.search(name, **kwargs)
         if search_resp:
@@ -82,8 +82,8 @@ def get_term(self, ontology, iri):
         """
         Gets the data for a given term
             Args:
-            ontology:   The name of the ontology
-            iri:        The IRI of a term
+            ontology: The name of the ontology
+            iri: The IRI of a term
         """
 
         url = self.ontology_term.format(ontology=ontology, iri=_dparse(iri))
@@ -117,7 +117,7 @@ def search(
         """
         Searches the OLS with the given term
 
-        @:param query_fields: By default the search is performed over term labels,
+        @:param query_fields: By default, the search is performed over term labels,
         synonyms, descriptions, identifiers and annotation properties. This option allows
         to specify the fields to query, the defaults are
         `{label, synonym, description, short_form, obo_id, annotations, logical_description, iri}`
@@ -196,7 +196,7 @@ def select(self, name, ontology=None, field_list=None):
         """Select terms,
         Tuned specifically to support applications such as autocomplete.
 
-        .. seealso:: https://www.ebi.ac.uk/ols/docs/api#_select
+        .. see also:: https://www.ebi.ac.uk/ols4/docs/api#_select
         """
         params = {"q": name}
         if ontology: