[General Questions and Answers] sw_men:
output of `fastboot getvar all` for my Xiaomi Poco C40 below.

cpu-abi:arm64-v8a
snapshot-update-status:none
super-partition-name:super

is-logical:uefi_sdi:no
is-logical:bl31_b:no
is-logical:fsc:no
is-logical:xbl_sdi:no
is-logical:bl31_a:no
is-logical:misc:no
is-logical:fsg:no
is-logical:persistbak:no
is-logical:bluetooth_b:no
is-logical:ddr_b:no
is-logical:bl2_b:no
is-logical:dsp_b:no
is-logical:rescue:no
is-logical:tos_b:no
is-logical:mmcblk0boot1:no
is-logical:boot_b:no
is-logical:vbmeta_system_b:no
is-logical:secdp:no
is-logical:fastboot_logo_a:no
is-logical:ffu:no
is-logical:rpm_b:no
is-logical:modemst2:no
is-logical:cust:no
is-logical:logdump:no
is-logical:bluetooth_a:no
is-logical:uboot_a:no
is-logical:persist:no
is-logical:fastboot_logo_b:no
is-logical:vendor_boot_b:no
is-logical:frp:no
is-logical:bl2_a:no
is-logical:tos_a:no
is-logical:dsp_a:no
is-logical:scp_b:no
is-logical:modemst1:no
is-logical:gsort:no
is-logical:otp:no
is-logical:rawdump:no
is-logical:rpm_a:no
is-logical:mmcblk0boot0:no
is-logical:minidump:no
is-logical:countrycode:no
is-logical:modem_a:no
is-logical:userdata:no
is-logical:dtbo_a:no
is-logical:scp_a:no
is-logical:logo_b:no
is-logical:logo_a:no
is-logical:uboot_b:no
is-logical:modem_b:no
is-logical:vbmeta_b:no
is-logical:dtbo_b:no
is-logical:ddr_a:no
is-logical:mmcblk0:no
is-logical:vbmeta_system_a:no
is-logical:metadata:no
is-logical:super:no
is-logical:boot_a:no
is-logical:vendor_boot_a:no
is-logical:vbmeta_a:no
is-logical:system_a:yes
is-logical:system_b:yes
is-logical:system_ext_a:yes
is-logical:system_ext_b:yes
is-logical:product_a:yes
is-logical:product_b:yes
is-logical:vendor_a:yes
is-logical:vendor_b:yes

battery-soc-ok:yes
battery-voltage:4406
off-mode-charge:0
treble-enabled:true
is-userspace:yes

partition-size:uefi_sdi:0x100000
partition-size:bl31_b:0x80000
partition-size:fsc:0x20000
partition-size:xbl_sdi:0xA000
partition-size:bl31_a:0x80000
partition-size:misc:0x100000
partition-size:fsg:0x300000
partition-size:persistbak:0x2000000
partition-size:bluetooth_b:0x100000
partition-size:ddr_b:0x100000
partition-size:bl2_b:0x80000
partition-size:dsp_b:0x4000000
partition-size:rescue:0x8000000
partition-size:tos_b:0x400000
partition-size:mmcblk0boot1:0x400000
partition-size:boot_b:0x6000000
partition-size:vbmeta_system_b:0x10000
partition-size:secdp:0x10000
partition-size:fastboot_logo_a:0x3000000
partition-size:ffu:0x800000
partition-size:rpm_b:0x80000
partition-size:modemst2:0x300000
partition-size:cust:0x40000000
partition-size:bluetooth_a:0x100000
partition-size:uboot_a:0x200000
partition-size:persist:0x2000000
partition-size:fastboot_logo_b:0x3000000
partition-size:vendor_boot_b:0x6000000
partition-size:frp:0x80000
partition-size:bl2_a:0x80000
partition-size:tos_a:0x400000
partition-size:dsp_a:0x4000000
partition-size:scp_b:0x100000
partition-size:modemst1:0x300000
partition-size:gsort:0x1000000
partition-size:otp:0x40000
partition-size:rawdump:0xC800000
partition-size:rpm_a:0x80000
partition-size:mmcblk0boot0:0x400000
partition-size:minidump:0x8000000
partition-size:countrycode:0x200000
partition-size:modem_a:0x8000000
partition-size:userdata:0x4723FBE00
partition-size:dtbo_a:0x1800000
partition-size:scp_a:0x100000
partition-size:logo_b:0x3000000
partition-size:logo_a:0x3000000
partition-size:uboot_b:0x200000
partition-size:modem_b:0x8000000
partition-size:vbmeta_b:0x10000
partition-size:dtbo_b:0x1800000
partition-size:ddr_a:0x100000
partition-size:vbmeta_system_a:0x10000
partition-size:metadata:0x1000000
partition-size:super:0x200000000
partition-size:boot_a:0x6000000
partition-size:vendor_boot_a:0x6000000
partition-size:vbmeta_a:0x10000
partition-size:system_a:0xB6F02000
partition-size:system_b:0x0
partition-size:system_ext_a:0x18E88000
partition-size:system_ext_b:0x0
partition-size:product_a:0x5B1F2000
partition-size:product_b:0x0
partition-size:vendor_a:0x44A27000
partition-size:vendor_b:0x0
partition-type:uefi_sdi:raw
partition-type:bl31_b:raw
partition-type:fsc:raw
partition-type:xbl_sdi:raw
partition-type:bl31_a:raw
partition-type:misc:raw
partition-type:fsg:raw
partition-type:persistbak:raw
partition-type:bluetooth_b:raw
partition-type:ddr_b:raw
partition-type:bl2_b:raw
partition-type:dsp_b:raw
partition-type:rescue:raw
partition-type:tos_b:raw
partition-type:mmcblk0boot1:raw
partition-type:boot_b:raw
partition-type:vbmeta_system_b:raw
partition-type:secdp:raw
partition-type:fastboot_logo_a:raw
partition-type:ffu:raw
partition-type:rpm_b:raw
partition-type:modemst2:raw
partition-type:cust:ext4
partition-type:logdump:raw
partition-type:bluetooth_a:raw
partition-type:uboot_a:raw
partition-type:persist:raw
partition-type:fastboot_logo_b:raw
partition-type:vendor_boot_b:raw
partition-type:frp:raw
partition-type:bl2_a:raw
partition-type:tos_a:raw
partition-type:dsp_a:raw
partition-type:scp_b:raw
partition-type:modemst1:raw
partition-type:gsort:raw
partition-type:otp:raw
partition-type:rawdump:raw
partition-type:rpm_a:raw
partition-type:mmcblk0boot0:raw
partition-type:minidump:raw
partition-type:countrycode:raw
partition-type:modem_a:raw
partition-type:userdata:f2fs
partition-type:dtbo_a:raw
partition-type:scp_a:raw
partition-type:logo_b:raw
partition-type:logo_a:raw
partition-type:uboot_b:raw
partition-type:modem_b:raw
partition-type:vbmeta_b:raw
partition-type:dtbo_b:raw
partition-type:ddr_a:raw
partition-type:mmcblk0:raw
partition-type:vbmeta_system_a:raw
partition-type:metadata:ext4
partition-type:super:raw
partition-type:boot_a:raw
partition-type:vendor_boot_a:raw
partition-type:vbmeta_a:raw
partition-type:system_a:raw
partition-type:system_b:raw
partition-type:system_ext_a:raw
partition-type:system_ext_b:raw
partition-type:product_a:raw
partition-type:product_b:raw
partition-type:vendor_a:raw
partition-type:vendor_b:raw
has-slot:uefi_sdi:no
has-slot:bl31:yes
has-slot:fsc:no
has-slot:xbl_sdi:no
has-slot:misc:no
has-slot:fsg:no
has-slot:persistbak:no
has-slot:bluetooth:yes
has-slot:ddr:yes
has-slot:bl2:yes
has-slot:dsp:yes
has-slot:rescue:no
has-slot:tos:yes
has-slot:mmcblk0boot1:no
has-slot:boot:yes
has-slot:vbmeta_system:yes
has-slot:secdp:no
has-slot:fastboot_logo:yes
has-slot:ffu:no
has-slot:rpm:yes
has-slot:modemst2:no
has-slot:cust:no
has-slot:logdump:no
has-slot:uboot:yes
has-slot:persist:no
has-slot:vendor_boot:yes
has-slot:frp:no
has-slot:scp:yes
has-slot:modemst1:no
has-slot:gsort:no
has-slot:otp:no
has-slot:rawdump:no
has-slot:mmcblk0boot0:no
has-slot:minidump:no
has-slot:countrycode:no
has-slot:modem:yes
has-slot:userdata:no
has-slot:dtbo:yes
has-slot:logo:yes
has-slot:vbmeta:yes
has-slot:mmcblk0:no
has-slot:metadata:no
has-slot:super:no
has-slot:system:yes
has-slot:system_ext:yes
has-slot:product:yes
has-slot:vendor:yes
security-patch-level:2022-05-01
vendor-fingerprint:Redmi/frost/frost:11/RD2A.211001.002/V13.0.6.0.RGFTRXM:user/release-keys
hw-revision:0
current-slot:a
serialno:bdc75187
product:frost
version-os:11
first-api-level:30
slot-count:2
max-download-size:0x10000000
version:0.4
version-baseband:
secure:yes
variant:NA
dynamic-partition:true
system-fingerprint:Redmi/frost/frost:11/RD2A.211001.002/V13.0.6.0.RGFTRXM:user/release-keys
version-bootloader:unknown
version-vndk:30
unlocked:no
all:
Finished. Total time: 0.670s

Since i am android newbie what is the meanings of all this variables? Is it documented somewere? (https://source.android.com/docs)

i am especially curious which is "has-slot:foobar:yes/no"

it says i have 2 slot and slot_a is active slot. is slot b ready to use as my will fits or some restriction apply here?

is unlocking it mandotory for using slot-b?