Scoreboards

effectset title of <who>'s scoreboard to <text>

The heading of the sidebar

set title of player's scoreboard to "&e&lMY SERVER"

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effectset line <n> of <who>'s scoreboard to <text>

Line 1 is the top line; there are 15

set line 2 of player's scoreboard to "&7Rank: &bVIP"

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structureupdate scoreboard of <who> every <duration>:since 1.7.64

The lines under it run now, and again that often, for as long as that player is on the server: a sidebar that keeps itself up to date, without a timer of its own. Asking again for the same player replaces what was running

on player join:
    set title of player's scoreboard to "&e&lMy server"
    update scoreboard of player every 2 seconds:
        set line 1 of player's scoreboard to "&7Coins: &f%{%player%.coins}%"
        set line 2 of player's scoreboard to "&7Online: &f%server.online_players%"

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effectstop updating scoreboard of <who>since 1.7.64

It is no longer kept up to date; what it shows stays

command /quiet:
    trigger:
        stop updating scoreboard of player
        send "&7Your sidebar is no longer kept up to date."

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effectdelete line <n> of <who>'s scoreboard

Remove one line

delete line 3 of player's scoreboard

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effectclear <who>'s scoreboard

Remove the sidebar and return to the server's normal scoreboard

clear player's scoreboard

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Guide and examples

Each player can have their own sidebar, built line by line.

set title of player's scoreboard to "&e&lSERVER NAME"
set line 1 of player's scoreboard to "&7Coins: &a%{%player%.coins}%"
set line 2 of player's scoreboard to "&7Rank: &bVIP"

Statement	Effect
`set title of <who>'s scoreboard to <text>`	The heading of the sidebar
`set line <n> of <who>'s scoreboard to <text>`	Line 1 is the top line; there are 15
`update scoreboard of <who> every <duration>:`	The lines under it run now, and again that often, for as long as that player is on the server: a sidebar that keeps itself up to date, without a timer of its own. Asking again for the same player replaces what was running
`stop updating scoreboard of <who>`	It is no longer kept up to date; what it shows stays
`delete line <n> of <who>'s scoreboard`	Remove one line
`clear <who>'s scoreboard`	Remove the sidebar and return to the server's normal scoreboard

The red numbers Minecraft puts beside every line are left out, on a Paper server for Minecraft 1.20.3 or newer; older servers and Spigot cannot hide them. sidebar-numbers: true in config.yml shows them again.

<who> is player or anything that gives a player name, such as {_name}'s scoreboard.

Animated sidebars. A line can be rewritten as often as every tick without flickering, so an animated or live-updating sidebar is a timer that sets the lines again:

every 1 second for all players:
    set title of player's scoreboard to "&e&lMY SERVER"
    set line 1 of player's scoreboard to "&7Coins: &a%{%player%.coins}%"
    set line 2 of player's scoreboard to "&7Ping: &f%player.ping% ms"
    set line 3 of player's scoreboard to "&7Online: &f%server.online_players%"

Lines can be about 120 characters long including colour codes; longer text is cut off.
A player sees one scoreboard at a time. While a HyperScript sidebar is shown it replaces the sidebar, name tags and tab-list teams of other scoreboard plugins for that player.
Sidebars disappear when the player logs out; set them again on join, which is also where update scoreboard of player every ...: belongs.