resolve WGLC comments

Author: QiufangMa

draft-ietf-netmod-schedule-yang.md

@@ -109,6 +109,9 @@ This document uses the YANG terminology defined in {{Section 3 of !RFC7950}}.
 
 The document makes use of the following terms:
 
+Recurrence Rule:
+: Refers to a rule or repeating pattern for recurring events. (See also {{Section 3.3.10 and Section 3.8.5.3 of !RFC5545}} for a comprehensive icalendar recurrence rule specification.)
+
 Frequency:
 : Characterizes the type of a recurrence rule. Values are taken from "FREQ" rule in {{Section 3.3.10 of !RFC5545}}.
 : For example, repeating events based on an interval of a second or more are

yang/ietf-schedule.yang

@@ -373,7 +373,8 @@ module ietf-schedule {
     choice period-type {
       description
         "Indicates the type of the time period. Two types are
-         supported.";
+         supported. If no choice is indicated, the period is 
+         considered to last forever.";
       case explicit {
         description
           "A period of time is identified by its start and its end.
@@ -442,7 +443,10 @@ module ietf-schedule {
        UTC. This grouping is intended to be machine-friendly.";
     container recurrence-first {
       description
-        "Specifies the first instance of the recurrence.";
+        "Specifies the first instance of the recurrence. If 
+         unspecified, the recurrence is considered to start from the
+         date and time when the recurrence pattern is first 
+         satisfied.";
       leaf start-time-utc {
         type yang:date-and-time;
         description
@@ -499,7 +503,10 @@ module ietf-schedule {
        is intended to be human-friendly.";
     container recurrence-first {
       description
-        "Specifies the first instance of the recurrence.";
+        "Specifies the first instance of the recurrence. If 
+         unspecified, the recurrence is considered to start from the
+         date and time when the recurrence pattern is first 
+         satisfied.";
       leaf start-time {
         type yang:date-and-time;
         description