message: handle special CCP4 spacegroup numbers
diff: @@ -1345,7 +1345,17 @@ export const SpacegroupNames: { [num: number]: SpacegroupName } = (function () {
  // return -1 if the spacegroup does not exist.
  export function getSpacegroupIndex(nameOrNumber: number | string | SpacegroupName): number {
  - const index = typeof nameOrNumber === 'number' ? nameOrNumber - 1 : ZeroBasedSpacegroupNumbers[nameOrNumber as SpacegroupName];
  + let index: number
  + if (typeof nameOrNumber === 'number') {
  + // used by CCP4, see http://www.ccp4.ac.uk/html/pointless.html#setting
  + if (nameOrNumber === 1017) index = 254
  + else if (nameOrNumber === 2017) index = 255
  + else if (nameOrNumber === 2018) index = 257
  + else if (nameOrNumber === 3018) index = 258
  + else index = nameOrNumber - 1
  + } else {
  + index = ZeroBasedSpacegroupNumbers[nameOrNumber as SpacegroupName];
  + }
  if (typeof index === 'undefined' || typeof SpacegroupNames[index] === 'undefined') return -1;
  return index;
  }
  \ No newline at end of file
  