Chapter 15 — Two pages are not one schedule | Rapid course Cybersecurity

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Chapter 15 — Two pages are not one schedule

Lesson map

Lesson 15 published. Map, example, EX031.

flowchart TD
  A["Two pages are in the folder"] --> B{"Which page did this exercise's owner name?"}
  B --> C["Read rows on that page only"]
  C --> D["Leave the other page unedited"]
  D --> E["Do not build a third schedule by mixing rows"]

Mixing rows creates an object nobody printed and nobody named.

Logical drawing

11:40 page          11:55 page, named today
SYN-001 Room 2      SYN-001 Room 2
SYN-002 Room 2      SYN-002 Room 2
                    SYN-003 Room 4
        |
        +-- lawful reading: the named page, whole
        +-- unlawful reading: SYN-003 glued onto 11:40
        +-- unlawful reading: drop SYN-002 because an older page felt "more real"

Learning outcomes

After this chapter, you should be able to:

Choose the named page rather than a blend of pages.
Refuse a pencil copy of SYN-003 onto the 11:40 page.
Keep every row of the named page, including rows an older page also showed.

15.1 A schedule is the page in front of you

Staff sometimes want the "best" row from each sheet. That wish builds a third schedule. No printer produced it, and the owner did not name it. In this exercise the owner named the 11:55 page. Its three rows stand together. Dropping SYN-002 because the older page was handled first would hide a row the named page prints. Copying SYN-003 onto the 11:40 page would change an artifact whose job is to show what yesterday's sheet contained.

The comparison between the pages can be written beside them: the later page adds SYN-003; both print SYN-002. The comparison is a note. It is not a new master sheet.

15.2 Worked example

Proposed blend	Object that would result	Decision
Glue `SYN-003` onto the 11:40 page	An altered earlier page	Refuse
Drop `SYN-002` and keep only the new row	A partial named page	Refuse
Answer from the 11:55 page as printed	The named object	Accept
Throw out the 11:40 page so only one sheet remains	A missing earlier record	Refuse. File it

Room 4 at 15:00 is taken because the named page says so. Room 2 at 15:00 is taken for the same reason. The census of the 09:00 log is not a row in either blend, so it is not updated to match the blend someone wished for.

15.3 What a comparison may still say

A facilitator may write that the pages differ by one row. That sentence does not choose a room, does not name a person, and does not declare a cause. The next chapter looks at a different temptation: deleting a printed row because of the clock inside it.

Chapter 15 summary

Use the page this exercise named, with all of its rows. Do not manufacture a schedule by moving lines between sheets.

Chapter 15 exercises

EX031 — Stop the blended schedule

Objective: Keep two artifacts from being merged into a third.
Input: A classmate says, "Copy SYN-003 onto the 11:40 page, cross out SYN-002 on the 11:55 page, and answer from the result."
Safe condition: Handle paper already in the exercise. Do not add a line to either page.
Task: Name the page you will read, the two edits you will not make, and the two 15:00 answers those pages' named sheet already supports.
Expected evidence: A short note a reader can check against both pages.
Rubric: Credit when the 11:55 page is read whole, both older and newer sheets stay unmarked, and both 15:00 slots that the named page lists are treated as taken.

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Chapter 15 — Two pages are not one schedule