请问一下 docker history 中的 buildkit.dockerfile.v0 是什么意思？

请问一下 docker history 中的 buildkit.dockerfile.v0 是什么意思？
IMAGE          CREATED         CREATED BY                                      SIZE      COMMENT
423a301d3603   9 days ago      /bin/sh -c bundle config mirror.https://ruby…   73B
<missing>      9 days ago      /bin/sh -c gem install bundler jekyll           212MB
<missing>      9 days ago      /bin/sh -c gem sources -a https://gems.ruby-…   12.9MB
<missing>      9 days ago      /bin/sh -c gem sources --remove https://ruby…   119B
<missing>      9 days ago      /bin/sh -c sed -i 's/#force_color_prompt/for…   3.3kB
<missing>      9 days ago      /bin/sh -c rm -rf /etc/cron.daily/apt           0B
<missing>      9 days ago      /bin/sh -c npm config set registry https://r…   2.02kB
<missing>      9 days ago      /bin/sh -c #(nop)  ENV PATH=/root/.nvm/versi…   0B
<missing>      9 days ago      /bin/sh -c #(nop)  ENV NODE_PATH=/root/.nvm/…   0B
<missing>      9 days ago      /bin/sh -c . ${NVM_DIR}/nvm.sh && nvm instal…   117MB
<missing>      9 days ago      /bin/sh -c #(nop)  ENV NVM_DIR=/root/.nvm       0B
<missing>      9 days ago      /bin/sh -c curl -s https://cdn.alomerry.com/…   1.34MB
<missing>      9 days ago      /bin/sh -c rm -rf /var/lib/apt/lists/* /var/…   0B
<missing>      9 days ago      /bin/sh -c apt-get clean                        0B
<missing>      9 days ago      /bin/sh -c DEBIAN_FRONTEND="noninteractive" …   342MB
<missing>      9 days ago      /bin/sh -c apt-get update                       61.4MB
<missing>      9 days ago      /bin/sh -c #(nop)  ENV LC_ALL=en_US.UTF-8       0B
<missing>      9 days ago      /bin/sh -c #(nop)  ENV LANGUAGE=en_US:en        0B
<missing>      9 days ago      /bin/sh -c #(nop)  ENV LANG=en_US.UTF-8         0B
<missing>      9 days ago      /bin/sh -c #(nop)  ENV HOME=/root               0B
<missing>      9 days ago      /bin/sh -c #(nop)  ENV DEBIAN_FRONTEND=nonin…   0B
<missing>      10 months ago   CMD ["/sbin/my_init"]                           0B        buildkit.dockerfile.v0
<missing>      10 months ago   ENV DEBIAN_FRONTEND=teletype LANG=en_US.UTF-…   0B        buildkit.dockerfile.v0
<missing>      10 months ago   RUN |1 QEMU_ARCH= /bin/sh -c /bd_build/prepa…   151MB     buildkit.dockerfile.v0
<missing>      10 months ago   COPY . /bd_build # buildkit                     40.4kB    buildkit.dockerfile.v0
<missing>      10 months ago   ARG QEMU_ARCH                                   0B        buildkit.dockerfile.v0
<missing>      10 months ago   /bin/sh -c #(nop)  CMD ["bash"]                 0B
<missing>      10 months ago   /bin/sh -c #(nop) ADD file:d2abf27fe2e8b0b5f…   72.8MB