this exercise, we selected 11 PNs for comprehensive suites of observations with [*Herschel*]{}, aiming to investigate the potential effects of X-rays on the physics and chemistry of the nebular gas and their manifestations in far-IR PN characteristics. Table \[objlist\] lists the whole HerPlaNS sample and its basic characteristics.

Observing Modes and Strategies\[modes\]
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In executing the HerPlaNS survey, we used all observing modes available with the photodetector array camera and spectrometer (PACS; @pacs) and the spectral and photometric imaging receiver (SPIRE; @spire). The log of observations is given in Table\[log\].

With PACS, we performed (1) dual-band imaging at 70$\mu$m (Blue band) and 160$\mu$m (Red band) with oversampling of the telescope point spread function (PSF; diffraction/wavefront error limited) and (2) integral-field-unit (IFU) spectroscopy by $5 \times 5$ spaxels (spectral-pixels), over 51–220$\mu$m. For two targets ( and ), an additional IFU spectroscopy was done at a higher spectral resolution with a $3 \times 3$ raster mapping (i.e., at higher spatial sampling) for specific far-IR fine-structure lines. With SPIRE, we carried out (1) triple-band imaging at 250$\mu$m (PSW band), 350$\mu$m (PMW band), and 500$\mu$m (PLW band), and (2) Fourier-transform spectrometer (FTS) spectroscopy in two overlapping bands to cover 194–672$\mu$m (SSW band over 194–313$\mu$m 