diff --git a/modules/core_api/fsw/inc/cfe_es.h b/modules/core_api/fsw/inc/cfe_es.h
index 5f4cee5de..ea87cf31b 100644
--- a/modules/core_api/fsw/inc/cfe_es.h
+++ b/modules/core_api/fsw/inc/cfe_es.h
@@ -1494,7 +1494,11 @@ CFE_Status_t CFE_ES_GetMemPoolStats(CFE_ES_MemPoolStats_t *BufPtr, CFE_ES_MemHan
 **        tool.
 **
 ** \par Assumptions, External Events, and Notes:
-
+**
+**  \c Marker limited to the range of 0 to
+**       #CFE_MISSION_ES_PERF_MAX_IDS - 1. Any performance ids outside of this
+**       range will be ignored and will be flagged as an error.
+**
 **  This function implements a circular buffer using an array.
 **      DataStart points to first stored entry
 **      DataEnd points to next available entry
diff --git a/modules/es/config/default_cfe_es_interface_cfg.h b/modules/es/config/default_cfe_es_interface_cfg.h
index 8189075d4..5fa4c574a 100644
--- a/modules/es/config/default_cfe_es_interface_cfg.h
+++ b/modules/es/config/default_cfe_es_interface_cfg.h
@@ -52,9 +52,14 @@
 **  \cfeescfg Define Max Number of Performance IDs for messages
 **
 **  \par Description:
-**       Defines the maximum number of perf ids allowed in command/telemetry messages
+**       Defines the maximum number of perf ids allowed.
 **
-**      This affects the layout of command/telemetry messages but does not affect run
+**       Each performance id is used to identify something that needs to be
+**       measured. Performance ids are limited to the range of 0 to
+**       #CFE_MISSION_ES_PERF_MAX_IDS - 1. Any performance ids outside of this
+**       range will be ignored and will be flagged as an error.
+**
+**      This affects the layout of telemetry messages but does not affect run
 **      time behavior or internal allocation.
 **
 **  \par Limits