Microservice-trace-2022/2021 MSCallGraph timestamp

Thank you for making these traces open-source! I have some questions about MSCallGraph timestamp, I've searched the issues but have not found an answer.
1) It seems like the timestamp for MSCallGraph table is not recorded in a 60s interval. Instead, it is recorded every ms (because it is continuous). Is that true?
2) The timestamp records the time when a request is sent from the um (not the time it receives the reply).

```
+--------------------+---------+----------+--------------------+-------+--------------------+--------------------+----+
| traceid|timestamp| rpcid| um|rpctype| dm| interface| rt|
+--------------------+---------+----------+--------------------+-------+--------------------+--------------------+----+
|73e7e49e159192966...| 6060435| 0| null| http|7695b43b41732a0f1...|27e468a9e023e3d90...|-159|
|73e7e49e159192966...| 6060471| 0.1.1| (?)| http|6f83eed1237572824...|f4e3cafeeedb15b33...|-121|
|73e7e49e159192966...| 6060472| 0.1.1.1|6f83eed1237572824...| mc|9653f5baba69c9fb5...| null| 0|
|73e7e49e159192966...| 6060482| 0.1.1.10|6f83eed1237572824...| mc|c964e78e1ee643bab...| null| 1|
|73e7e49e159192966...| 6060483| 0.1.1.11|6f83eed1237572824...| mc|59eea9a5f7ed349c3...| null| 1|
|73e7e49e159192966...| 6060485| 0.1.1.12|6f83eed1237572824...| mc|22fa7dbf2ea117787...| null| 0|
|73e7e49e159192966...| 6060485| 0.1.1.13|6f83eed1237572824...| mc|22fa7dbf2ea117787...| null| 1|
|73e7e49e159192966...| 6060486| 0.1.1.14|6f83eed1237572824...| mc|46a6d5047ff9337b3...| null| 0|
|73e7e49e159192966...| 6060486| 0.1.1.15|6f83eed1237572824...| mc|46a6d5047ff9337b3...| null| 1|
```

Begin with the MSCallGraph 2022/2021 table and the sample rows in this issue. Confirm the timestamp cadence and whether it denotes request send or reply receipt, then record the answers in the relevant dataset documentation; no file or test is named in the payload.

Written by the indexing model from the issue text.