stroke-dashoffset

html,
body,
svg {
  height: 100%;
}

<svg viewBox="-3 0 33 10" xmlns="http://www.w3.org/2000/svg">
  <!-- No dash array -->
  <line x1="0" y1="1" x2="30" y2="1" stroke="black" />

  <!-- No dash offset -->
  <line x1="0" y1="3" x2="30" y2="3" stroke="black" stroke-dasharray="3 1" />

  <!--
  The start of the dash array computation
  is pulled by 3 user units
  -->
  <line
    x1="0"
    y1="5"
    x2="30"
    y2="5"
    stroke="black"
    stroke-dasharray="3 1"
    stroke-dashoffset="3" />

  <!--
  The start of the dash array computation
  is pushed by 3 user units
  -->
  <line
    x1="0"
    y1="7"
    x2="30"
    y2="7"
    stroke="black"
    stroke-dasharray="3 1"
    stroke-dashoffset="-3" />

  <!--
  The start of the dash array computation
  is pulled by 1 user units which ends up
  in the same rendering as the previous example
  -->
  <line
    x1="0"
    y1="9"
    x2="30"
    y2="9"
    stroke="black"
    stroke-dasharray="3 1"
    stroke-dashoffset="1" />

  <!--
  the following red lines highlight the
  offset of the dash array for each line
  -->
  <path d="M0,5 h-3 M0,7 h3 M0,9 h-1" stroke="rgb(255 0 0 / 50%)" />
</svg>