diff --git a/EDMC.py b/EDMC.py
index 842e0a33..cfd019e5 100755
--- a/EDMC.py
+++ b/EDMC.py
@@ -290,7 +290,7 @@ sys.path: {sys.path}'''
                 sys.exit(EXIT_SERVER)
 
             # noinspection DuplicatedCode
-            if isinstance(capi_response, companion.CAPIFailedRequest):
+            if isinstance(capi_response, companion.EDMCCAPIFailedRequest):
                 logger.trace_if('capi.worker', f'Failed Request: {capi_response.message}')
                 if capi_response.exception:
                     raise capi_response.exception
diff --git a/EDMarketConnector.py b/EDMarketConnector.py
index 940b4a40..6ec7b32c 100755
--- a/EDMarketConnector.py
+++ b/EDMarketConnector.py
@@ -947,11 +947,11 @@ class AppWindow(object):
         play_bad: bool = False
         err: Optional[str] = None
 
-        capi_response: Union[companion.CAPIFailedRequest, companion.EDMCCAPIResponse]
+        capi_response: Union[companion.EDMCCAPIFailedRequest, companion.EDMCCAPIResponse]
         try:
             logger.trace_if('capi.worker', 'Pulling answer off queue')
             capi_response = self.capi_response_queue.get(block=False)
-            if isinstance(capi_response, companion.CAPIFailedRequest):
+            if isinstance(capi_response, companion.EDMCCAPIFailedRequest):
                 logger.trace_if('capi.worker', f'Failed Request: {capi_response.message}')
                 if capi_response.exception:
                     raise capi_response.exception
diff --git a/companion.py b/companion.py
index 2d83a38c..85a4e4f6 100644
--- a/companion.py
+++ b/companion.py
@@ -560,7 +560,7 @@ class EDMCCAPIResponse(EDMCCAPIReturn):
         self.capi_data: CAPIData = capi_data  # Frontier CAPI response, possibly augmented (station query)
 
 
-class CAPIFailedRequest(EDMCCAPIReturn):
+class EDMCCAPIFailedRequest(EDMCCAPIReturn):
     """CAPI failed query error class."""
 
     def __init__(
@@ -594,10 +594,17 @@ class Session(object):
         self.retrying = False  # Avoid infinite loop when successful auth / unsuccessful query
         self.tk_master: Optional[tk.Tk] = None
 
-        self.capi_raw_data = CAPIDataRaw()
-        logger.debug('Starting CAPI queries thread...')
-        self.capi_response_queue: Queue
+        self.capi_raw_data = CAPIDataRaw()  # Cache of raw replies from CAPI service
+        # Queue that holds requests for CAPI queries, the items should always
+        # be EDMCCAPIRequest objects.
         self.capi_query_queue: Queue = Queue()
+        # This queue is used to pass the result, possibly a failure, of CAPI
+        # queries back to the requesting code (technically anything checking
+        # this queue, but it should be either EDMarketConnector.AppWindow or
+        # EDMC.py).  Items may be EDMCCAPIResponse or EDMCCAPIFailedRequest.
+        # NB: This is created by the caller and set using self.set_capi_response_queue().
+        self.capi_response_queue: Queue
+        logger.debug('Starting CAPI queries thread...')
         self.capi_query_thread = threading.Thread(
             target=self.capi_query_worker,
             daemon=True,
@@ -893,7 +900,7 @@ class Session(object):
                 except Exception as e:
                     self.capi_response_queue.put(
                         (
-                            CAPIFailedRequest(
+                            EDMCCAPIFailedRequest(
                                 message=e.args,
                                 exception=e,
                                 query_time=query.query_time,
@@ -920,7 +927,7 @@ class Session(object):
                 except Exception as e:
                     self.capi_response_queue.put(
                         (
-                            CAPIFailedRequest(
+                            EDMCCAPIFailedRequest(
                                 message=e.args,
                                 exception=e,
                                 query_time=query.query_time,